Updated

Supporters of a leftist president candidate who are occupying the cultural and financial heart of Mexico's capital said Tuesday they planned to expand protests aimed at pressuring authorities to order an election recount.

The backers of Andres Manuel Lopez Obrador -- who finished an agonizingly close second place in the official but still uncertified vote count -- are considering seizing more streets, and some newly elected officials of his Democratic Revolution Party may refuse to take office in protest.

A more combative atmosphere spread throughout the motley protest camp of hundreds of tents pitched on the asphalt of the city's main Reforma Avenue. The leftist candidate said he owes it to his supporters to keep the protest going until the court agrees to recount all 41 million votes.

CountryWatch: Mexico

"They want us to sit back and do nothing, but that would be equivalent to backing down, to betrayal, and we will never do that," Lopez Obrador said during a morning tour of the five-mile long protest encampment, which has practically cut off the city's downtown and choked traffic throughout.

Lopez Obrador, who stepped down as Mexico City's mayor to run for president, has alleged that widespread fraud and mathematical errors tainted the July 2 vote.

Conservative Felipe Calderon, who led by less than 0.6 percent, or roughly 240,00 votes, in official vote counts, accused Lopez Obrador of having "kidnapped" the capital and the 20 million residents of the greater metropolitan area.

"They want to win in the streets, something they weren't able to win at the voting booth," Calderon told reporters.

Lopez Obrador appeared to win a small victory when the Federal Electoral Tribunal's seven judges voted unanimously late Monday to consider a possible recount while also ruling on the hundreds of challenges in individual districts.

But the tribunal also dealt an apparent blow to Lopez Obrador's "shotgun" strategy of citing thousands of irregularities at the 130,000 polling places, saying it would not roll all the legal challenges into a single case, but would consider each on its own merits.

Lopez Obrador's top campaign aide, Jesus Ortega, said the street blockade "is serving to channel in a peaceful and legal direction the anger, indignation and sometimes rage that people feel." He promised "there will be more acts of civil disobedience," and said they would not be announced beforehand.

Democratic Revolution candidates who made major gains in congressional and local races have begun threatening to refuse to take their posts in protest, a move that could paralyze some levels of government.

"I will refuse to take office, if that is the strategy we decide on," said Leonel Luna, who was elected to lead one of the city's 16 boroughs. Some congressional winners have said the same.

As the ramshackle camps of tents, tarps, lawn chairs and improvised barricades snarled commuter traffic for a second straight day, television news focused on the anger of motorists enduring hours-long commutes.

Lopez Obrador acknowledged the criticism and urged Mexicans not to turn to violence. He counseled supporters to tell angry commuters that "this is a fight for democracy that will benefit everyone."