Pollsters said during a conference organized by the Federal Electoral Institute, or IFE, that they expected Mexico's presidential election next month to get tight in the home stretch amid polarization.

Representatives of several polling firms said the gap between frontrunner Enrique Peña Nieto and his closest rival, Andres Manuel Lopez Obrador, would narrow as election day gets closer.

Nearly all the polls conducted so far have shown Peña Nieto, of the Institutional Revolutionary Party, or PRI, in the lead, but Lopez Obrador, the candidate of a leftist coalition, has been gaining ground and the election could produce a photo-finish as in 2006.

In the 2006 race, "the campaign started with a nine-point advantage for Lopez Obrador and ended practically tied," with Felipe Calderon eventually edging out the former Mexico City mayor, Consulta Mitofsky chief Roy Campos said.

"Formally speaking, we would have to say that there is a candidate with a greater likelihood of winning, but he does not have the certainty of winning. And of the other two, there is one (Lopez Obrador) who started lower and now appears to have greater chances" than the number three in the polls, conservative Josefina Vazquez Mota, Campos said.

ISA polling firm CEO Ricardo de la Peña, for his part, noted that seven polls gave Peña Nieto a lead of more than 10 points, while three others put him in the lead, but with much smaller margins of victory.

"It's hard to know if (these polls) will have a tendency to converge or will maintain the divergence, De la Peña told Efe.

Pollster Ana Cristina Covarrubias, who founded Demotecnia, said it was "normal" for the electorate to "feel a certain confusion" about who to believe and that a poll "is good" when it shows differences.

The "Yo soy 132" student movement, meanwhile, denied its members were involved in an attack earlier this week on Peña Nieto's motorcade.

About 30 people armed with sticks and stones attacked the PRI candidate's motorcade in a city in Puebla, a state in central Mexico, on Tuesday.

People close to Peña Nieto told some media outlets that a group of young people from the movement staged the attack, a charge that was denied by a Yo soy 132 spokesman.

"The movement has stated from the beginning that it is peaceful, both saying this and acting according to this principle, so we distance ourselves from any act of violence," Saul Alvidrez, one of the movement's spokesmen, told Efe.

The goal of the PRI, which governed Mexico from 1929 to 2000, is to diminish the movement's legitimacy and credibility, Alvidrez said.

The protest movement started on May 11, when Peña Nieto visited the Universidad Iberoamericana and was jeered by students, who accused him of being a candidate "manufactured" by the powerful Televisa network.

Those in Peña Nieto's inner circle and some media pundits downplayed the incident, accusing the students of being agitators.

The students counterattacked by making a video that was posted on YouTube.

The criticism led to the birth of the "Somos mas de 131" (We Are More Than 131) movement, which took its name from the number of students who appeared in the video and later evolved into the "Yo soy 132" (I Am 132) movement when students from other universities joined the protests.

The young people also created the Twitter hash tag #LaMarchaYoSoy132 to get their message out to supporters and the public.

One of the main demands made by the non-partisan student movement is that Mexico's media be democratized and provide balanced coverage.

Mexico will hold its presidential election on July 1, selecting a successor to President Felipe Calderon.

Nearly 80 million Mexicans will be eligible to vote for a new president, 628 legislators and thousands of other officials in the general elections. EFE