There will be no negotiations with rival candidates because the only acceptable option is to invalidate Mexico's July 1 presidential election and hold a new vote, leftist candidate Andres Manuel Lopez Obrador said.

"There is only one agreement, the one that invalidates the presidential election, we are not going to allow any agreement that in any way that gets built over the swamp, over the filth, the main thing is to defend the votes of the citizens," Lopez Obrador told some 4,000 supporters at a rally Sunday in Puebla.

Lopez Obrador met with supporters in Puebla, located about 125 kilometers (77 miles) from Mexico City, and urged them to work with the 32 people's assemblies organized across the country to shed light on "electoral fraud."

A summary of the irregularities committed by the Institutional Revolutionary Party, or PRI, will be submitted to the TEPJF electoral court in the middle of this week, Lopez Obrador said.

PRI candidate Enrique Peña Nieto won the presidential election with 38.21 percent of the vote, while Lopez Obrador took second place with 31.59 percent, according to the final official results released by the Federal Electoral Institute, or IFE.

The TEPJF has until Aug. 31 to issue a ruling on the challenge filed by Lopez Obrador's Progressive Movement coalition, either certifying Peña Nieto the winner or calling for a new vote.

Lopez Obrador challenged the election results, alleging that the PRI and its allies exceeded campaign spending limits and engaged in vote-buying with funds obtained from illicit sources.

"We have solid evidence so no questions remain, so no legal arguments can be used and the elections declared valid, which are clearly a violation of the constitution," Lopez Obrador said.

The evidence will be presented to the TEPJF so there is no excuse for not invalidating the elections and Congress can name an interim president to serve until new elections are held, the politician, who was the candidate of a coalition of leftist parties led by the Party of the Democratic Revolution, or PRD, said.

"There is evidence that they used front companies to finance everything related to getting out the vote for the PRI," Lopez Obrador said.

Lopez Obrador lost the 2006 presidential election to Felipe Calderon, of the National Action Party, or PAN, by 0.56 percent and has never recognized the results, claiming victory in the contest and declaring himself "president-elect."

"No violence, no provocations," Lopez Obrador told his supporters, referring to his National Plan for the Defense of Democracy and Dignity.

"Only those who are in the wrong resort to violence, and we are right," Lopez Obrador said.

Lopez Obrador said recently that he planned to hold an "Expofraude" on Aug. 12 at which evidence of election irregularities would be presented to the public.

The PRD and the conservative PAN announced last month that they planned to jointly file a complaint with the Attorney General's Office on alleged money laundering by the PRI.

The two parties also filed a request with the IFE for a speedy investigation of allegations of irregular use of campaign funds by the PRI, which governed Mexico from 1929 to 2000. EFE