That's the left-center party that very nearly won the presidency in 2006.
http://stopthedrugwar.org/chronicle/548/mexico_PRD_legalizationLatin America: Mexico's PRD May Call for Legalization
Articlefrom Drug War Chronicle, Issue #548, 8/22/08
According to Mexican press reports this week, Mexico's Partido de la Revolución Democrática (PRD -- Democratic Revolution Party) is preparing to consider legalization of the drug trade as a response to the wave of narco-violence that has swept the country in the last year and a half. Around 5,000 people have been killed in prohibition-related violence since President Felipe Calderón escalated Mexico's long-running drug war by enlisting the military in the fight in December 2006.
PRD presidential candidate Andrés Manuel López Obrador came within a handful of votes of winning the presidency in 2006, and the party remains the second strongest political force in the country, behind the ruling Partido Acción Nacional (PAN -- National Action Party). But because of party infighting since that election, the PRD may drop into third place after this year's midterm elections, behind both the PAN and the Partido Revolucionario Institucional (PRI -- Revolutionary Institutional Party).
According to the Mexico City newspaper El Universal, the PRD's national council is calling on the party's legislators to begin discussing legalization as part of a "grand national accord" to deal with violence and insecurity in the country. The proposal came from the PRD's New Left faction, led by Jesús Zambrano, and was approved unanimously by the national council.
In an interview with Mexico's Televisa TV network, the PRD coordinator in the lower house, Javier González Garza, upped the ante, saying legalization should be considered not only in Mexico, but also in the US. "We can't continue thinking that we are going to combat the problem of drug trafficking without more radical measures, and one of them has to be the legalization of drugs in the United States," he said. "After the United States will we continue with Mexico? Of course, or both at the same time... This war, the way it is outlined, is going to be lost, we're all going to lose, it makes no sense and there need to be some changes."
Some 25,000 Mexican army troops are fighting drug traffickers along the border and in a number of major cities and drug-growing areas. Many observers blame the spike in violence -- more people have been killed already this year than in all of last year -- on the aggressive stance of the Calderón government. But the US government is pleased; it recently passed a $1.4 billion, three-year anti-drug assistance package for Mexico, most of which will go to beefing up military and police capabilities.