MEXICO CITY (Reuters) - Mexico's leftist presidential hopeful Andres Manuel Lopez Obrador pushed into second place behind opposition frontrunner Enrique Pena Nieto with just seven weeks to go before the vote, a poll showed on Tuesday.
Lopez Obrador, who narrowly lost the 2006 race to President Felipe Calderon, had 20.5 percent support in the poll by Consulta Mitofsky, up 1.4 percent from last week, overtaking the No. 2 spot for the first time in the survey.
But the silver-haired former mayor of Mexico City is still trailing Pena Nieto from the opposition Institutional Revolutionary Party (PRI) by more than 17 points.
Lopez Obrador is steadily gaining ground on the ruling conservative National Action Party (PAN) as voters turn away from their candidate Josefina Vazquez Mota. Calderon is barred from running for re-election.
Vazquez Mota's campaign is sputtering after a contentious primary vote led to party infighting. Voters are also disenchanted with rising drug violence and shocking cartel massacres during Calderon's administration.
She slipped into third place for the first time in the Mitofsky poll with 20.1 percent, down 0.7 percent from last week's survey, reducing her chances of becoming Mexico's first woman president.
Pena Nieto has held a commanding lead throughout the campaign with 37.9 percent support in Tuesday's poll, down half a percent from the previous week.
The young and good-looking former governor, is trying to put a new face on the PRI, which ruled Mexico for seven decades before losing to the PAN in 2000.
His efforts to woo youth voters, though, were met with marches organized over the weekend by mostly university students, lambasting Pena Nieto and the PRI's autocratic past.
Lopez Obrador, running for a coalition of leftist parties headed by the Democratic Revolution Party (PRD), may be able to galvanize youth voters who reject the PRI but also Calderon's government ahead of the July 1 vote.
He says his candidacy represents change, but many voters are still skeptical of his past. Lopez Obrador lost by a tiny margin in 2006 and rejected the election result, organizing noisy protests that choked the capital city for months after the vote.
The Mitofsky poll, conducted between May 18-20, interviewed 1,000 eligible voters and had a margin of error of 3.1 percentage points.
The daily GEA-ISA poll published in Milenio newspaper on Tuesday gave Pena Nieto a nearly 20-point lead over his closest rival.
(Reporting by David Alire Garcia; Editing by Lisa Shumaker)