The general-secretary of Mexico's ruling party accused leftist presidential candidate Andres Manuel Lopez Obrador on Sunday of heading a "schizophrenic" movement that turns suddenly from peaceful dialogue to aggressive confrontation.

Lopez Obrador has called nationwide demonstrations and filed a court challenge to vote counts that show he lost the July 2 election to ruling National Action Party candidate Felipe Calderon by 244,000 votes, or less than 0.6 percent.

Cesar Nava of the conservative National Action Party criticized promises by Lopez Obrador aides to expand protests against alleged election fraud.

"It's a new threat that reflects the schizophrenia in the movement headed by Andres Manuel Lopez Obrador," Nava said. "Their lack of respect for the law knows no limits.

Lopez Obrador and supporters are demanding a ballot-by-ballot recount of all 41 million votes cast. So far the protests and marches have been nonviolent.

But Nava said backers of Lopez Obrador "want to impose their will through blackmail and threats."

On Saturday, Lopez Obrador aide Gerardo Fernandez said the demonstrations would get bigger, promising that more than 2 million people will march in Mexico City on July 30. A crowd of at least 300,000 rallied in the capital's main square last week to support Lopez Obrador.

While there has been no violence, both sides have used strong language.

Lopez Obrador has called President Vicente Fox — also a member of National Action — a "traitor to democracy" and has complained of "fascist" attacks against him.

Calderon, meanwhile, has accused Lopez Obrador of being a "danger to Mexico" and compared him to a drunk driver heading the wrong way down a freeway.

The Federal Electoral Tribunal has until Aug. 31 to rule on the fraud allegations and must declare a president-elect by Sept. 6.