New Electoral Laws Could Accelerate Mexico’s Democratic Decline

Mexico is currently undergoing an erosion of democratic norms that has intensified since Sheinbaum took office in 2024.

Proposed Reforms to Mexico’s Electoral System

On March 4, 2026, Mexican President Claudia Sheinbaum submitted a constitutional reform initiative to Mexico’s Chamber of Deputies — the lower house of Congress, roughly equivalent to the U.S. House of Representatives — that would reshape the country’s electoral system.

The proposal arrived at a critical moment for Mexico’s democracy. Mexico is currently undergoing an erosion of democratic norms that has intensified since Sheinbaum took office in 2024. More specifically, its electoral rules and authorities are among the remaining institutional checks and balances on centralized executive power in the country. This brief analyzes several of the most consequential provisions of Sheinbaum’s initial reform proposal, as well as the subsequent Plan B initiative, and assesses their implications for the quality of Mexican democracy and the integrity of its elections.

Key Elements of the Reform Proposals

While the new initiative is less far-reaching than the electoral reforms proposed by former President Andrés Manuel López Obrador in February 2024 — a sweeping package that would have likely weakened key pillars of Mexico’s electoral framework — the Sheinbaum proposal still contained substantial departures from established democratic practices. It sought to reduce public financing and media access for political parties, eliminate proportional representation in the Senate, and introduce regulation of artificial intelligence that could potentially enable censorship. Some critics also argued that these reforms could further open the possibility of organized criminal interests interfering in election processes.

On March 11, opposition parties and dissenting members of the ruling coalition prevented Sheinbaum from acquiring the two-thirds majority required to change the Mexican Constitution. The president then submitted a second, narrower constitutional reform initiative — commonly referred to as Plan B — which the Senate approved on March 25 after stripping its most controversial provision. This brief examines the key provisions of both proposals, considers their potential implications for Mexico’s democratic framework, and outlines the legislative pathways that remain available to Sheinbaum and the National Regeneration Movement (MORENA) Party.

Beyond constitutional reform, the government retains the option of enacting electoral changes through standard legislation requiring only a simple majority in Congress. Such legislation would require little to no support from MORENA’s allies and would likely face minimal judicial oversight, as MORENA’s previous reforms have largely weakened the federal judiciary, including the Supreme Court.

Democratic Challenges in Mexico

Upon taking office in 2018, López Obrador launched a series of proposals targeting the institutional checks on the executive by reforming the following: the judiciary, autonomous regulatory agencies, and the National Electoral Institute (INE) — Mexico’s independent election management body — which has earned a strong reputation for organizing professional and trustworthy elections. In February 2024, López Obrador submitted a package of 20 constitutional and legislative reform initiatives — known as Plan C — to Congress. These proposals sought to transform several key dimensions of the Mexican state, from the judiciary, electoral system, energy policy, to the expanded role of the military in civilian government.

Electoral Outcomes and Legislative Power

MORENA and its allies — the Labor Party (PT) and the Ecologist Green Party of Mexico (PVEM), two satellite parties that typically compete in coalition with MORENA — won the presidency with Claudia Sheinbaum, securing nearly 60% of the vote. In congressional elections, the ruling coalition also achieved success, though with a slightly smaller margin, winning approximately 55% of the vote. The governing coalition ultimately secured a two-thirds supermajority in both chambers of Congress.

This was achieved through a combination of legislative defections in the Senate and a contentious interpretation of the constitutional provisions governing the allocation of seats in the Chamber of Deputies, which formally limit any party to no more than 8% overrepresentation relative to its vote share. This opened the door to constitutional reforms at will.

With MORENA’s supermajority, nearly all of López Obrador’s reforms were approved. The most significant was the judicial reform, which removed all sitting federal and state judges, from trial courts to the Supreme Court. It replaced them through a system of popular elections for judges and justices, a practice not undertaken in any modern constitutional democracy. The reform also eliminated tenure protections, dismantled the professional judicial career system, and created new governing bodies — the Judicial Discipline Tribunal and the Judicial Administration Body — both subject to political influence.

By mid-2025, Mexico had a new Supreme Court widely viewed as politically partisan and a judiciary staffed via a selection process that critics deemed inadequate. These judicial reforms along with others have considerably weakened institutional checks on executive power in Mexico.

Status of Electoral Reform Efforts

López Obrador’s far-reaching electoral proposals were the only major reforms left pending before he left office. This was largely a matter of pragmatism rather than principle: MORENA could not simultaneously restructure the judiciary and the electoral system because the INE was needed to organize the June 2025 judicial elections.

In addition, the electoral reform originally proposed by López Obrador created considerable political complications within the governing coalition. Several of its provisions directly affected the interests of MORENA’s two legislative allies — PT and PVEM — both of which hold seats in Congress and benefit from the current system of proportional representation and public financing.

A presidential commission composed entirely of MORENA and its allies — no opposition representatives or election experts were included — spent months drafting the reform without outside review. Following these deliberations and unsuccessful negotiations with MORENA’s legislative allies, Sheinbaum submitted the first version of her initiative in March 2026. The initiative was rejected by the Chamber of Deputies on March 11 (discussed above). The president subsequently submitted a second constitutional reform — Plan B — on March 17, and has signaled that ordinary legislation requiring only a simple majority may follow.

Reductions in Public Financing and Media Access

Among the most consequential provisions of the initial proposal was the weakening of two pillars of electoral competition central to Mexico’s democratic system: public financing for political parties and guaranteed access to broadcast media.

Public Funding for Elections

The proposal included a reduction in public financing for political parties by 25%. This change would lower the formula used to calculate public funding from 65% to 48.75% of the daily value of Mexico’s benchmark unit — known as Unidad de Medida y Actualización (UMA) — multiplied by the total number of registered voters. The UMA is a government benchmark used to calculate public payments, fines, and a wide range of legal funding formulas. Had the provision been enacted, approximately one out of every four pesos in public funding toward electoral costs would no longer have been allocated as such.

Guaranteed Access to Broadcast Media

The initiative also would have decreased the broadcast time available to political parties during campaign periods from 48 to 35 minutes per day — a cut of more than 27%. This change is particularly significant because Mexico’s Constitution prohibits political parties, candidates, and private actors from purchasing political advertising on radio and television. Instead, parties receive free access to broadcast airtime allocated by the electoral authority, primarily based on each party’s share of the vote in the previous election. The reform would have substantially reduced guaranteed access to broadcast media, which has historically underpinned a more level playing field in Mexico’s elections.

Issue of Illicit Funds

Had the reform been enacted, these reductions would have occurred within an electoral system already at risk: A large share of campaign funding is neither legally acquired nor reported. Estimates suggest that for every peso of officially reported spending, as many as 15 pesos of illicit money circulate — from wide-ranging sources that include government contractors, diverted public funds, and organized crime. Public financing provides a partial counterweight to these reports’ estimates by providing a baseline of legal resources and limiting the role of illicit funding in political campaigns.

A decrease in public campaign funding by 25% would likely have deepened parties’ reliance on illicit money. This impact would fall disproportionately on the opposition, which lacks the advantages of incumbency. By virtue of holding power at the federal, state, and municipal levels, MORENA benefits from structural advantages that could lead to easier access of illicit financing. It has greater opportunities to divert public resources, and its candidates — because they are most likely to win — are more attractive to private actors willing to invest illegally obtained money in electoral outcomes. Although the government presented  this reform as an effort to advance “republican austerity,” in practice it could have tilted  the playing field even further in favor of the ruling party.

Proposed Removal of Senate Proportional Representation

Under the existing system, each of Mexico’s 32 states elects three senators: two for the party or coalition that wins the most votes (first-past-the-post), and one “first minority” seat for the runner-up party. The remaining 32 seats are distributed proportionally based on each party’s share of the national vote.

Under the proposed reform, the Senate would have been reduced from 128 to 96 members by eliminating those 32 proportional representation. With the chamber limited to state-level winners and runners-up, votes for parties finishing below second place would receive no representation. As political scientist Javier Aparicio has demonstrated, this change would have benefited MORENA and disadvantaged smaller parties.

This matters because Mexico’s governments already faces acute legislative overrepresentation. In the 2024 elections, MORENA and its allies won about 54% of the vote for the Chamber of Deputies but ultimately secured 73% of the seats. This outcome stemmed from a contentious interpretation of the constitutional rules specifically designed to cap overrepresentation and shield Mexico’s Constitution from being unilaterally amended by a political force lacking a true supermajority of votes. For this reason, legal scholars have argued that the interpretation amounted to a technical “fraud against the Constitution.”

The Senate reflects a similar, though slightly smaller, imbalance: MORENA holds a two-thirds supermajority despite winning just over half of the national vote. This disparity stems partly from the electoral system and partly from postelection defections by opposition senators — shifts frequently attributed to political pressure. In one notable example, a senator from the conservative National Action Party (PAN) voted in favor of the judicial reform, and shortly afterward, an arrest warrant against him was dropped.

Rather than mitigating the existing overrepresentation, Sheinbaum’s initial proposal would have deepened these distortions. As a result, MORENA could secure an even larger share of seats with fewer votes, further entrenching its legislative dominance.

Artificial Intelligence Regulations in Elections

The initial proposal introduced a constitutional mandate that all election-related content modified or generated through artificial intelligence — or via “any other technology” — be labeled by its creator. While concerns about AI-generated disinformation in elections are legitimate and widely shared across democracies, the broad strokes of the proposed regulation posed several potential risks:

• Vague scope: Identifying “all content related” — directly or indirectly — to the “electoral processes” would have been a difficult task. Expecting broadcasters, digital platforms, and other intermediaries to monitor and verify all such content would be impractical (or impossible) due to time constraints and limited resources.
• Technical overreach: Including the phrase, “any other technology,” significantly expands the rule’s reach. Given this imprecise language, the labeling requirement could conceivably apply to content edited with common tools, such as basic smartphone photo editors, Canva, or Photoshop.
• Compliance liability: Assigning broadcasters and digital platforms the responsibility to “identify, prevent the dissemination of, and warn about” unlabeled content would have imposed a far-reaching liability on television networks, radio broadcasters, and digital platforms. This could considerably delay or disrupt operations, given the scale of the monitoring required and the risk of sanctions for noncompliance.
• Prior restraint: Creating a system of prior restraint would have required intermediaries to monitor and, thus, impede expression before it reaches the public. Under international human rights standards, liability for speech must generally be imposed after publication, not before. By reversing this principle, the proposed framework would have opened the door to censorship.

Benefits of the First Proposal

While many of its measures would likely weaken Mexico’s democratic norms, the initiative also included substantive reforms to enhance electoral competition and safeguard the integrity of campaign financing:

• Competitive races: It introduced a mechanism that would have allocated 100 of the 200 proportional representation seats in the Chamber of Deputies to losing candidates who performed well in their districts. In turn, the proposal could have incentivized more competitive local races.
• Campaign finance integrity: The proposal elevated existing prohibitions on foreign financing, the use of illicit resources, and cash contributions to the constitutional level. Constitutionalizing the secondary law provisions would have fortified the existing framework for campaign finance integrity.

Rejection of the First Proposal

On March 11, the Chamber of Deputies voted down Sheinbaum’s initial constitutional reform. The bill fell short of the two-thirds majority required for constitutional amendments. MORENA's coalition partners, the PT and the PVEM, withheld their support. The provisions analyzed in the preceding sections — reductions in public financing and broadcast time, the elimination of Senate proportional representation seats, the AI regulatory framework, and the proposal’s positive elements — were all part of this initial initiative. None were carried over to Plan B, a narrower constitutional reform analyzed below.

Sheinbaum’s Second Constitutional Reform Initiative (Plan B)

Following the defeat of her initial proposal, Sheinbaum submitted a second constitutional reform initiative to the Senate on March 17. Framed officially as a measure to “reduce privileges and strengthen the recall referendum,” the initiative was narrower in scope than its predecessor. It did not include the provisions on public financing, proportional representation, or artificial intelligence regulation that had been part of the initial proposal. Instead, Plan B focused on three main areas: restructuring the presidential recall election, capping the size of municipal governments, and limiting the budgets of state legislatures.

Recall Referendum and Presidential Neutrality

The most consequential provision of Plan B sought to restructure Mexico’s presidential recall election. The initiative proposed three changes to Article 35 of the Constitution:

1. It would have enabled the recall vote to coincide with Mexico’s 2027 midterm elections, in which voters will renew the entire 500-seat Chamber of Deputies, elect 17 governors, and choose approximately 5,200 judicial positions, along with thousands of local offices. Current rules prohibit such overlap: The recall can only be requested after the third year of a presidential term and must be held on a date separate from federal or local elections. The initiative would have allowed it to be requested after the second or third year and scheduled for the first Sunday of June of the corresponding year.
2. It explicitly authorized the president to “disseminate the process and promote the vote in her favor.”
3. It would have expanded the president’s ability to use public resources for messaging during the recall period. Activities not classified as “contracted” advertising — including daily press conferences, official tours, and public events — would have remained permissible throughout the process.

These changes would represent a significant departure from Mexico’s existing neutrality framework. Article 134 of the Constitution requires all public servants to “apply the public resources under their responsibility impartially, without influencing the fairness of competition among political parties.” Article 35 further provides that only the autonomous electoral authorities (primarily the INE) may promote the recall election, and that their promotion must be “objective, impartial, and for informational purposes.” Campaigning by any other authorities or the political parties regarding the recall vote is not permitted.

The initiative would have reversed this structure, granting Sheinbaum the constitutional right to campaign in her own favor and to use public resources for that purpose. Opposition parties would have remained barred from promoting or opposing the recall. Given Sheinbaum’s relatively high approval ratings and polling suggesting that MORENA’s support has begun to decline, critics argued that placing Sheinbaum’s name on the 2027 ballot alongside MORENA’s candidates would generate a coattail effect benefiting the ruling party — with no constitutional mechanism for opposing forces to respond.

Other Provisions and Outcome of Plan B

Plan B also included measures targeting local government. It proposed a constitutional cap on the size of municipal governments — limiting each municipality to a maximum of 15 council members, regardless of population. It also imposed a uniform ceiling on state legislature budgets at 0.7% of each state’s annual expenditures.

The PT — MORENA’s coalition partner — opposed the recall election changes, arguing that holding the recall concurrently with the 2027 midterm elections would erode its own support at the ballot box and benefit MORENA. PT leader Alberto Anaya warned that the concurrent scheduling would create inequity in the electoral contest. In the end, the Senate approved the remaining provisions on March 25, but stripped the recall election changes entirely.

The bill still requires approval by the Chamber of Deputies and ratification by at least 17 of Mexico’s 32 state legislatures. Given MORENA’s majorities in both chambers and its influence in most state legislatures, approval is widely expected. The ruling party could also pursue modifications to secondary electoral legislation, a path that requires only a simple majority in Congress.

Sheinbaum’s Remaining Legislative Pathway

The Secondary Legislation Alternative

Although both of Sheinbaum’s constitutional reform initiatives failed to pass in full, the ruling party retains a clear legislative pathway. MORENA holds a simple majority in both chambers of Congress — sufficient to amend secondary electoral legislation without the support of the PT or the PVEM. Such changes — while not as substantial as the constitutional amendments proposed by López Obrador in 2024 — are likely to pass and would represent another step in Mexico’s democratic backsliding.

The precedent is well established. López Obrador took a similar approach in 2022 when his proposed constitutional reform — commonly referred to as “Plan A” — did not secure the required supermajority in Congress. He then introduced a statutory reform known as “Plan B,” which, although less sweeping, still introduced significant changes to the electoral framework.

Lopez Obrador’s Plan B consisted of two legislative decrees that amended more than 350 provisions across several electoral laws, altering key aspects of Mexico’s electoral system. Among its most consequential elements were measures that:

• Weakened the INE’s permanent professional structure.
• Reduced the operational and technical capacity of the electoral authority.
• Restricted the oversight powers of the electoral tribunal.
• Imposed budgetary constraints that could affect the protection of political rights.
• Relaxed long-standing constitutional prohibitions on government propaganda during electoral periods.

The reform also opened the door for the federal executive branch to play a role in shaping the national voter registry — a function traditionally insulated from political influence.

Impacts of Judicial Reform

The recent judicial reforms in Mexico have extensively weakened the Supreme Court’s ability to act as a check on executive power. The trajectory from the López Obrador era to the Sheinbaum administration illustrates the significant policy shifts reshaping Mexico’s Supreme Court:

• Precedent of independence: Under López Obrador, the Supreme Court struck down the Plan B legislative package. This ruling was rooted in decades of jurisprudence holding that “rushed” legislation — passed without proper deliberation — violated constitutional lawmaking processes.
• Mechanism of political influence: This safeguard against expediated legislation was largely possible because the court retained a meaningful degree of independence. However, the subsequent judicial reform lead to the removal of all sitting judges and the ruling party’s dominance within the federal judiciary.
• Implications of one-party majority: While the court previously used “procedural irregularities” to block unconstitutional overreach, the newly MORENA-led bench is unlikely to challenge Sheinbaum’s upcoming legislation.

The new Supreme Court installed after the 2025 judicial reforms is widely regarded as politically aligned with the ruling coalition, raising concerns about the erosion of judicial oversight and the scope of potentially unconstitutional legislation. Empirical analyses of its early decisions suggest that, despite occasional internal disagreements, the court has consistently ruled in favor of the administration’s political program. Given that a statutory electoral reform would require only a simple majority in Congress, Sheinbaum’s legislation is likely to have staying power.

Shifting Democratic Trajectory in Mexico

Sheinbaum’s two constitutional reform proposals were less far-reaching than the package López Obrador advanced in 2024. However, they signal a continuation of the same trajectory. 

The initial proposal sought to reduce resources available for electoral competition, would have strengthened the ruling party’s advantages in legislative representation, and introduced a regulatory framework for artificial intelligence that raised questions about freedom of expression.

The second proposal (Plan B) sought to restructure the presidential recall election in ways that would have undermined the constitutional framework of governmental neutrality during electoral processes.

Although both proposals included some positive elements, these would not fully offset broader concerns. Furthermore, the ruling party retains the ability to reshape the electoral framework through secondary legislation, potentially with minimal limited reliance on coalition partners and reduced judicial oversight.

Taken together, these developments suggest a period of continued institutional adjustments. As these changes unfold, they may carry important implications for Mexico’s electoral system — long a central pillar of its democratic transition.

This publication was produced by Rice University’s Baker Institute for Public Policy. Wherever feasible, the material was reviewed by outside experts prior to release. Any errors or omissions are solely the responsibility of the author(s).

This material may be quoted or reproduced without prior permission, provided appropriate credit is given to the author(s) and Rice University’s Baker Institute for Public Policy. The views expressed herein are those of the individual author(s) and do not necessarily represent the views of Rice University’s Baker Institute for Public Policy.