The Institutional Revolutionary Party's decision to support a government effort to pass a constitutional amendment extending Mexico's National Guard will likely weaken the coalition between the main opposition parties, boosting the government ahead of gubernatorial elections. In a Sept. 14 vote in the lower house of the Mexican legislature, 64 legislators from the Institutional Revolutionary Party (PRI), the country's main opposition party, joined the governing National Regeneration Movement-led alliance to vote in favor of a constitutional amendment to extend the existence of the National Guard through 2028. The National Action Party and the Democratic Revolution Party, which with the PRI belong to the opposition coalition Va por Mexico, criticized the PRI and questioned the future of the opposition bloc's legislative agenda. 

• In 2019, President Andres Manuel Lopez Obrador promoted a constitutional amendment that created the National Guard and authorized continued military involvement in policing until 2024. In early September, PRI congresswoman Yolanda de la Torre put forward a constitutional amendment to extend the National Guard's existence through 2028.
• On Sept. 14, 335 legislators voted in favor — just one more than the number required for a constitutional amendment — versus 152 opposed coming from opposition parties PAN, PRD and center left party Movimiento Ciudadano, and one abstention.
• The Senate will debate and vote on the constitutional amendment the week of Sept. 19, which is likely to be a contentious process. The National Regeneration Movement (MORENA) and its allies will need the support of at least 10 PRI senators to reach the two-thirds majority required for passage. As PRI President Alejandro Moreno supports the initiative, it will likely pass.

The PRI move will likely create a prolonged fracture in the opposition coalition that will benefit the Mexican government ahead of 2023 gubernatorial elections. The PRI probably is supporting the extension of the National Guard to prevent a temporary decrease in the size of Mexico's security forces while the country rebuilds its national police force, which the party believes would result in increased cartel activity and migrants. But PRI support for the amendment will weaken the Va por Mexico oppositional alliance, decreasing communication between its members and risking reduced cohesion on other policies. Such a fracture in the opposition coalition will likely weaken the PRI's party ahead of June 2023 gubernatorial elections in Mexico and Coahuila states, in which PRI governors will face opponents from MORENA and other parties. 

• While MORENA and its allies control enough seats in the Mexican legislature to pass ordinary legislation, it lacks the numbers to pass constitutional reforms, which means that they need support from the opposition to do so. Va por Mexico was formed in late 2020 to prevent the government from reforming the constitution. The PRI, PRD and PAN have been political rivals for decades, however, which means that their coalition is ideologically fractured. After the formation of the coalition, the three parties continued to field their own candidates and compete in legislative and local elections.
• Though individual members of the PAN and PRD have called for a formal rupture to the Va por Mexico coalition, the two parties' leadership has only criticized the PRI's voting choices, not announced a formal break. 

The PRI will likely continue to vote against the government's initiatives in areas such as energy or electoral reforms, while its support of the constitutional amendment ensures that the National Guard will remain Mexico's predominant security body. PRI leadership has indicated strong opposition to the government on other policies such as efforts to bolster state-owned energy companies against the private sector and carry out electoral reforms. While the PRI may be more willing to support some aspects of MORENA's policy platform, such as increased funding for agricultural production, it will likely be unwilling to support key aspects of Lopez Obrador's policy platform unless the government waters them down. This means that Lopez Obrador will likely be forced to implement his keystone policies via legislation that could be challenged in court; the government previously has implemented legislation later blocked as unconstitutional. Meanwhile, subsequent administrations can reverse policy implemented via regulatory bodies. PRI support for the constitutional amendment will likely lead to security continuity and prevent disruptions in trade, as the National Guard ensures security in places such as ports and ports of entry along the U.S.-Mexico border. 

• The PRI voted against MORENA's proposed constitutional amendment aimed at bolstering Mexico's state-owned energy companies against private competitors April 17. Party leadership also announced that it would refuse to negotiate a potential amendment to eliminate the National Electoral Institute in favor of a different electoral institute after Lopez Obrador's MORENA party suggested the two parties negotiate over their two separate constitutional reform proposals. 
• As recently as early September, PRI legislators and senators voted against MORENA-proposed legislation seeking to bring the National Guard under the purview of the military.