New Bill Proposes Electoral Reform in Mexico

Mexican President Claudia Sheinbaum on March 4, 2026, submitted to the House of Representatives a bill proposing a decree to amend, add and repeal various provisions of the Mexican Constitution in electoral matters. The bill was received by the President of the House of Representatives, Kenia López Rabadán, who referred it to the United Committees on Constitutional Affairs and Political-Electoral Reform for consideration and the issuance of a legislative opinion.

The reform seeks to redesign several components of Mexico's electoral system with three main objectives:

• reduce the costs of the political-electoral system
• strengthen democratic legitimacy
• update regulation in response to new technological and financial risks

The proposed bill also introduces adjustments to public financing for political parties, changes to the composition of Congress, as well as new oversight rules and mechanisms to regulate the use of artificial intelligence (AI) in electoral processes.

Based on the argument that Mexico's electoral system has become costly, bureaucratic and distant from citizens, the bill therefore proposes an institutional reconfiguration that preserves the core principles of political pluralism, while establishing rules aimed at improving representation, strengthening citizen participation and preventing illicit or technological interference in electoral competition.

Main Proposals and Modifications

Proportional Representation and Plurinominal Seats

The bill does not eliminate the principle of proportional representation, but it substantially modifies the mechanism through which plurinominal seats in the House of Representatives are allocated.

Currently, the 200 proportional representation seats are assigned through regional party lists determined by political parties. The reform proposes a hybrid system in which 100 seats would be allocated to candidates who competed in single-member districts and obtained the highest vote percentages without winning the election, under the "best runner-up" principle.

Meanwhile, the remaining 100 seats would be elected through direct voting in five regional constituencies, including representation for Mexican citizens residing abroad. The objective is to reduce the perception of closed party appointments and bring proportional representation closer to actual electoral results.

Reduction of the Senate and Adjustment to the Composition of Congress

In the Senate, the bill eliminates the 32 proportional representation seats, reducing the size of the Upper Chamber from 128 members to 96 members, who would be elected exclusively through majority vote and first minority in each federal entity.

If approved, this change would represent a 25 percent reduction in the number of senators, with implications for both legislative spending and political representation.

Meanwhile, the House of Representatives would maintain its current composition of 500 members, although with a redesign of the mechanism used to allocate proportional representation seats.

Reduction of Public Financing for Political Parties

One of the most significant changes included in the reform is the reduction of ordinary public financing for political parties.

Currently, public financing is calculated by multiplying the electoral roll by 65 percent of the unit of measurement and update (Unidad de Medida y Actualización or UMA). The reform proposes reducing this factor to 48.75 percent of the UMA, representing an approximate 25 percent reduction in public resources allocated to political parties.

The internal distribution formula would remain unchanged, as follows:

• 30 percent distributed equally among political parties
• 70 percent allocated proportionally according to the votes obtained

New Model for Electoral Financial Oversight

The bill introduces stricter financial oversight mechanisms for electoral campaigns and political parties.

Among the most significant changes are a daily report to the National Electoral Institute (Instituto Nacional Electoral or INE) on financial transactions by parties and candidates by institutions in the financial system. Other changes include:

• a ban on cash contributions, requiring funds to be transferred through the financial system
• an obligation to report transactions involving virtual assets, foreign currency and significant financial transactions
• coordination among electoral authorities, financial institutions and financial intelligence agencies to verify candidacies

Regulation of the Use of Artificial Intelligence and Manipulated Content

The bill incorporates, for the first time in the constitutional text, provisions regulating the use of artificial intelligence in electoral processes. It establishes that any electoral content generated or altered through AI must be labeled.

Media outlets and digital platforms will be required to identify, warn about or prevent the dissemination of unlabeled content.

The law also will establish sanctions and responsibilities for platforms and broadcast concessionaires.

Changes in Political Communication and Campaign Advertising

The reform proposes adjustments to official broadcast time in the media. The time available for political advertising on radio and television during campaigns would be reduced from 48 minutes to 35 minutes per day, administered by the INE. This reduction aims to simplify and reduce advertising saturation.

Participatory Democracy and Popular Consultations

The bill expands the constitutional recognition of citizen participation mechanisms. Among the proposals are:

• explicit recognition of referendums, plebiscites and popular consultations at the municipal and state levels
• a maximum threshold of 2 percent of the electoral roll to request direct democracy mechanisms
• binding results when at least 40 percent of the electorate participates

Political Participation of Mexican Citizens Residing Abroad

The bill proposes that Mexican citizens residing abroad may be elected as proportional representation representatives, integrating them into the regional constituencies.

It also establishes the obligation to create a permanent electoral register for Mexicans living abroad and to guarantee their participation in the election of deputies starting with the 2027 electoral process.

This change is interpreted as strengthening the political recognition of the migrant community, which has traditionally been limited to voting from abroad, and opens the door to more direct parliamentary representation.

Vote Counting and Electoral Processes

District vote counts would begin immediately upon receipt of the first electoral package at the district councils, both in federal and local elections. It should be noted that, under the current framework, the formal count begins on later dates established by electoral law.

The new scheme seeks to accelerate vote-counting processes and reduce periods of post-electoral uncertainty, although it would also require significant logistical adjustments for the electoral authority.

Affirmative Actions and Historically Underrepresented Groups

The constitutional reform incorporates the obligation for political parties and electoral authorities to guarantee affirmative actions in the selection of candidates for historically underrepresented communities, including Indigenous, Afro-Mexican and other groups facing political underrepresentation.

This practice, which the INE had primarily developed through administrative guidelines, would now be elevated to constitutional status.

Legislative Process

Approval in the Congress

The electoral bill submitted by President Sheinbaum must first be analyzed and issued a legislative opinion in the committees of the House of Representatives as the chamber of origin, and subsequently discussed and voted on in the Plenary. To advance, it requires a qualified majority of two-thirds of the legislators present. Once approved, the bill is sent to the Senate, where the same procedure is repeated, and it must also be approved by a qualified majority.

Ratification by State Legislatures

If both chambers of the Congress approve the same text, the bill is sent to the legislatures of the federal entities. For the constitutional reform to be valid, it must be approved by at least 17 of the 32 state legislatures.

Declaration, Promulgation and Entry into Force

Once the majority of state legislatures has approved the reform, the Congress issues the Declaration of Constitutional Validity. The decree is then sent to the Federal Executive for promulgation and subsequent publication in the Federal Registry, at which point the reform enters into force in accordance with the timelines established in the transitory provisions.

Composition of Congress if the Reform is Approved

The following images show what the composition of Congress will be if the bill is approved:

If you have any questions about the bill reforming the Mexican electoral system, please contact the authors.

Information contained in this alert is for the general education and knowledge of our readers. It is not designed to be, and should not be used as, the sole source of information when analyzing and resolving a legal problem, and it should not be substituted for legal advice, which relies on a specific factual analysis. Moreover, the laws of each jurisdiction are different and are constantly changing. This information is not intended to create, and receipt of it does not constitute, an attorney-client relationship. If you have specific questions regarding a particular fact situation, we urge you to consult the authors of this publication, your Holland & Knight representative or other competent legal counsel.