MEXICO CITY (Reuters) - Mexican leftist Andres Manuel Lopez Obrador inched ahead in the presidential race, according to an opinion poll published on Tuesday, after accusing his rival's brother-in-law of tax dodging.
The survey in Milenio newspaper gave Lopez Obrador 34.2 percent, up almost 1 percentage point from a poll by the daily in late May. The conservative ruling party's candidate Felipe Calderon had 31 percent, down 2 points.
Most other recent polls have put the pair in a tie before the July 2 vote. The El Universal newspaper gave Calderon a three-point lead in a survey on Monday.
Lopez Obrador said in a live televised debate last week that Calderon's businessman brother-in-law evaded paying taxes and received large government contracts while Calderon was energy minister.
The leftist former mayor of Mexico City later dumped boxes of what he said were documents to prove his claim at Calderon's campaign headquarters in a stunt that won him media coverage.
Calderon has repeatedly denied any misconduct, but the scandal is tarnishing his image. His campaign has put strong emphasis on his "clean hands" in a country stained with corruption.
Investment bank Merrill Lynch said Lopez Obrador has gained support since the debate with attack advertising against Calderon.
"Lopez Obrador appears to have won the post-debate with charges that Calderon used his position as energy minister to grant government contracts to the Internet services companies of his brother-in-law, Diego Zavala," it said in a note.
"An unprecedented 180 TV spots in only two days promoting charges against Calderon appear to have paid off," it said.
Tuesday's poll had a margin of error of 2.6 points, so the leading two candidates are technically still very close.
Roberto Madrazo, of the Institutional Revolutionary Party, was close behind in third place in the poll at 29.6 percent, almost unchanged from his support in late May.
Pollster Maria de las Heras, who carried out the Milenio poll for the newspaper, said she calculated that Lopez Obrador had gained around 700,000 supporters since the July 6 debate and Calderon lost a similar amount of votes.
"Lopez Obrador gained in the last few weeks and this poll confirms to me that this race continues to be very close among the top three candidates," she said.
Milenio interviewed 1,500 people in a five-day period after the debate for the survey.
