MEXICO CITY (AP) -- Mexico's interior secretary on Tuesday said the supporters of a leftist presidential candidate who are occupying a central part of the capital have set up an "illegal blockade" and it was up to the mayor to guarantee order.

Carlos Abascal, the top-ranking member of outgoing President Vicente Fox's Cabinet, stopped short of ordering Mexico City Mayor Alejandro Encinas to force the protesters to leave Reforma Avenue, which transverses the financial and cultural heart of this city of 20 million. But he said he had "implored him, in accordance with his responsibilities, to guarantee the order and liberty of all citizens in the face of the illegal blockade."

Supporters of Andres Manuel Lopez Obrador, who finished an agonizingly close second place in the official but still uncertified vote count from the July 2 election, have blocked the avenue since late Sunday, erecting tents the length of the stylish boulevard and in the heart of the historic central plaza.

The protesters are considering seizing more streets, and some newly elected officials of Lopez Obrador's Democratic Revolution Party may refuse to take office in protest.

Lopez Obrador stepped down as Mexico City mayor last year and remains immensely popular here, though the street blockades have crippled traffic, hurt businesses and caused the stock market and currency to falter.

Fox's administration has said it will not intervene in the protest unless Encinas — a member of Lopez Obrador's party — asks it to. Addressing about 40,000 supporters near the tent city where he himself is sleeping, Lopez Obrador did not mention Abascal by name, but said that those who oppose him "say they support the rule of law, but actually are in favor of the rule of crookedness."

He also called on supporters to fortify their camps along Reforma.

Lopez Obrador wants Mexico's electoral court to order a full recount of all 41 million ballots casts last month. Felipe Calderon, the former energy secretary and member of Fox's conservative National Action Party who won the election according to the official tally, has said that a vote-by-vote recount is unnecessary and illegal.

A more combative atmosphere had been spreading throughout the motley protest camp, but Lopez Obrador urged supporters to remain peaceful late Tuesday. "We have to act with prudence even though our blood is boiling," he said. "If we are right, we have no reason to be hostile to the media."

He also reached out to the seven judges who compose the Federal Electoral Tribunal, which must weigh challenges to the election filed by both sides and declare a president-elect by Sept. 6. "I respectfully call on the judges to do their work with patriotism and feeling," he said. "The decision that they are going to make is historic and we want is something fair, that they recount the votes and that way we can resolve the problem."

Lopez Obrador has said widespread fraud and mathematical errors tainted the election.

Mexican stocks fell for the second day Tuesday, with the key IPC index closing 0.6 percent lower. The peso also weakened slightly, losses analysts blamed in part on the street blockades.

Lopez Obrador appeared to win a small victory when the electoral court voted unanimously late Monday to consider a possible recount while also ruling on the hundreds of challenges in individual districts.