A grassroots movement led by young people and organized via social-networking sites is playing an increasingly active role in Mexico's presidential election, threatening to undermine Institutional Revolutionary Party, or PRI, candidate Enrique Peña Nieto's frontrunner position in the polls.

The movement has organized massive street protests in less than two weeks and made the role of the media in a democracy a campaign issue, injecting energy into what had been one of the most boring races on record in Mexico.

The grassroots movement got its start on May 11 at the Universidad Iberoamericana, where Peña Nieto, who is the candidate of the PRI and the Mexican Green Party, or PVEM, was jeered by students of the private university, prompting some analysts to christen the date "Black Friday."

Peña Nieto was criticized for his performance as governor of Mexico state, especially the May 4, 2006, police crackdown on protesters in San Salvador Atenco that left two people dead and more than 200 others under arrest.

PRI members downplayed the incident and accused the students of doing the bidding of certain political interests in exchange for favors, a charge that only made the situation worse.

The young people counterattacked with a YouTube video defending their right to express their views and giving birth to the "Somos mas de 131" (We Are More Than 131) movement and the Twitter hash tag #LaMarchaYoSoy132, which allows people to search for a tweets on a common topic.

Protesters rallied under the movement's banner on May 18 at the headquarters of media giant Televisa, rejecting Peña Nieto's candidacy and calling for balanced coverage in the media, a request that prompted the network to ask them to debate the issue.

The #LaMarchaYoSoy132 hash tag took off the next day on Twitter and demonstrations were staged in about 20 cities across Mexico.

Protesters in Mexico City carried banners that said "Mexicano, despierta, ya basta" (Mexicans, Wake Up, Enough Already) and "Peña Nieto tiene tele, pero nosotros tenemos las calles y las redes" (Peña Nieto has TV, but we have the streets and the networks), directly challenging the PRI, which governed Mexico from 1929 to 2000, and the media.

Peña Nieto, for his part, responded to the growing movement against him by unveiling a manifesto Monday that calls for freedom of expression and the right to protest.

The "Manifiesto por una Presidencia democratica" (Manifesto for a Democratic Presidency) was crafted as a response to the questions posed by a group of intellectuals on March 27 to Mexico's four presidential candidates.

The 10-point document establishes the political principles by which Peña Nieto says he will govern if he wins the July 1 presidential election.

The goal is "to build a united and strong Mexico based on recognition and respect for the diversity of our convictions and ideas," Peña Nieto said.

Leftist candidate Andres Manuel Lopez Obrador, meanwhile, attended a rally Monday that drew more than 10,000 students to Mexico City's Tlatelolco Plaza and called on young people to use their summer vacations to fight for democracy and bring change to Mexico.

"I know that many university students are getting ready to go on vacation, so I am proposing that you offer these vacations to democracy, to working for democracy," Lopez Obrador told the students from various institutions.

Lopez Obrador is appealing to students in the final weeks of the election campaign in an effort to cut into Peña Nieto's wide lead in the polls.

Poll results published last week by the El Universal newspaper showed Lopez Obrador, standard-bearer of the Party of the Democratic Revolution, or PRD, the Workers Party, or PT, and the Citizens Movement, taking second place in the race from conservative Josefina Vazquez Mota, of the governing National Action Party, or PAN.

Lopez Obrador, according to the Buendia&Laredo poll, is drawing the support of 24.8 percent of likely voters, while Vazquez Mota is getting 23.1 percent support.

Peña Nieto is drawing the support of 49.6 percent of likely voters ahead of the July 1 presidential election.

The presidential campaign ends on June 27, four days before some 80 million Mexicans head to the polls to cast ballots for a new president, 628 legislators and thousands of other officials. EFE