MEXICO CITY (Reuters) - Mexican left-wing presidential candidate Andres Manuel Lopez Obrador extended his lead to 14 points in an opinion poll completed last week, with a fight between his opponents over accusations of financial wrongdoing weighing on their support.

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Lopez Obrador has 35 percent support ahead of the July 1 vote according to the survey by polling firm Parametria, published by Reuters on Wednesday ahead of wider publication.

That compared with 34 percent and an 11 percentage point lead in a survey by the same company a month earlier.

Lopez Obrador appeared to benefit from a tussle for second place between his opponents, who have spent the last couple of weeks accusing each other of corruption, with the former Mexico City mayor sitting comfortably above the fray.

“The fight for second place is damaging them both,” Parametria founder Francisco Abundis said. “For citizens, these disputes are very tiring.”

In the number two spot, Ricardo Anaya of left-right coalition “For Mexico in Front,” slipped to 21 percent support, from 23 percent in the previous poll.

Former finance minister and ruling Institutional Revolutionary Party (PRI) hopeful Jose Antonio Meade slid for the second consecutive month, to 16 percent from 18 percent.

The poll was taken between Feb. 24 and March 1, as the mudslinging was intensifying.

At the center of the Anaya controversy is the purchase and sale of real estate in an industrial park in the state of Queretaro between 2014 and 2016, which Meade says led to illicit enrichment by his rival. Anaya said the deals were legitimate.

Anaya responded by pointing to irregularities detected by federal auditors worth millions of dollars in the accounts of the ministry for social development when it was run by Rosario Robles, now minister for agrarian, land and urban development.

Anaya’s campaign says some of the embezzlement of public funds happened when Meade was minister at the ministry, an accusation Meade’s team calls a “lie.”

The poll is based on interviews with 800 people in their homes; 12 percent either did not answer, responded that they did not know or could not choose a candidate listed. The poll has a margin of error of 3.5 percentage points.

Lopez Obrador’s 14-point lead is larger than in other recent polls done before the recent furor over Anaya’s business dealings. Mexico’s Reforma newspaper gave him an 8-point lead, while polling organization Consulta Mitofsky put the gap at just 5 percentage points.

Independent hopeful and former first lady Margarita Zavala surged to 10 percent of the vote in the Parametria poll, while on-leave Nuevo Leon Governor Jaime Rodriguez grew to 5 percent.

The campaign starts officially on March 30. Candidates will participate in the first television debate on April 22 in Mexico City.