Second decade (1999–2009)
After the election of Vicente Fox, PAN candidate, the PRD announced that it would not file any complaints about the elections. This was a shift in strategy from the usual protests of fraud. However, some local PRD activist groups filed complaints but these were turned down by the PRD and the electoral court.
The former mayor of Mexico City, Andrés Manuel López Obrador, was the presidential candidate for the "Coalición por el Bien de Todos" (Coalition for the Good of All) in the 2006 presidential elections. López Obrador ran against Felipe Calderón, PAN candidate, and Roberto Madrazo, PRI candidate.
López Obrador's campaign relied on citizen's networks (redes ciudadanas) that focused on mobilizing the public to campaign. This strategy focused on López Obrador as an individual and not the PRD. This was worrisome to PRD leaders because they thought that the PRD's concerns would not be addressed. However, many party members thought that López Obrador would win so these concerns were not addressed.
After the general election of 2 July 2006 and a recount of the 9.09% of the ballot tally sheets which supposedly presented irregularities, the Federal Electoral Institute recorded the vote results in favor of Felipe Calderón by a margin of 0.58 percent, about 243,000 votes. These results were later validated by the Federal Electoral Tribunal. However, the PRD claimed that there was election fraud. The claims of election fraud have been rejected by the Federal Electoral Tribunal (TEPJF), which considered these "notoriously out of order" ("notoriamente improcedente") and certified PAN's candidate Felipe Calderón as the winner.
López Obrador then rallied his supporters to hold demonstrations in the capital, Mexico City. These demonstrations were organized by the PRD, whose stronghold is in Mexico City. The PRD had called for demonstrations and set up camps in the capital's main square, blocking one of its main avenues (Paseo de la Reforma) for six weeks to demand a recount of all votes, which was not granted. The camps were later dismantled after a confrontation with the Mexican Army became likely.
On 5 September, the Federal Electoral Tribunal announced that there was not enough evidence of electoral fraud that legitimized Calderon as president. This caused López Obrador to maintain his campaign of civil disobedience and declared himself as "Legitimate President" in a "public open vote" (people in the main square raising their hands). López Obrador did not recognize the legitimacy of Calderón as president. The PRD was criticized for not complying with the democratic system that it had lauded and helped create. However, the PRD could not agree on whether they should move forward and cooperate with the current system and contribute to policy or take on an uncompromising stance in an attempt to overturn the current system. This split later trickled on to other things such as electoral and petroleum reforms where one part of the party wanted to cooperate while the other refused to out of allegiance to López Obrador.
In 2008, after bitter infighting within the party, Jesús Ortega, an opponent of Andrés Manuel López Obrador, was elected party president. In the 2009 legislative elections, López Obrador supported two smaller parties while maintaining his ties to the PRD.
The party had enjoyed a reputation of honesty unmatched by its competitors, until the "Video Scandals" a series of videos where notable party members were taped receiving cash funds or betting large sums of money in a Las Vegas casino.
Later, another video was recorded by Cuba's government where Carlos Ahumada, the man providing the money, states that members of the PRI and PAN, PRD's rivals, were planning the situation presented in the first video as part of a plot against Andrés Manuel López Obrador to discredit him as a possible presidential candidate.
Party members who were seen on the videotapes were expelled from the party, but those who were supposedly associated, but never legally charged, are still active members.