MEXICO CITY – Felipe Calderon was declared president-elect Tuesday after two months of uncertainty, but his ability to rule remained in doubt with Andres Manuel Lopez Obrador vowing to lead a parallel leftist government from the streets.

The unanimous decision by the Federal Electoral Tribunal rejected allegations of systematic fraud and awarded Calderon the presidency by 233,831 votes out of 41.6 million cast in the July 2 elections – a margin of 0.56 percent. The ruling cannot be appealed.

Calderon now must win over millions of Mexicans angry that President Vicente Fox didn’t make good on promises of sweeping change – and fend off thousands of radicalized leftists who say they will stop at nothing to undermine his presidency.

Lopez Obrador has said he won’t recognize the new government and vows to block Calderon from taking power Dec. 1. Protesters outside the tribunal wept as the decision was announced and set off firecrackers that shook the building.

“We aren’t going to let him govern!” Thomas Jimenez, a 30-year-old law student, screamed as hundreds of protesters threw eggs and trash at the courthouse.

The decision by the seven judges – who have split their votes in disputes about other elections – also found that Fox endangered the election by making statements that favored Calderon, and that business leaders broke the law by paying for ads against Lopez Obrador, who promised to govern on behalf of the poor.

But the problems weren’t serious enough to annul the results, they said.

“There are no perfect elections,” said Judge Alfonsina Berta Navarro Hidalgo.

The court rejected most of Lopez Obrador’s allegations, including his claim that an ad campaign comparing him to Venezuelan President Hugo Chavez unfairly swayed voters.

The court also dismissed Lopez Obrador’s claim of subliminal messages in television ads by pro-Calderon businesses.

The court’s president, Leonel Castillo, called on Mexicans to unite and mend the deep divisions the election revealed.

“I hope we conclude this electoral process leaving confrontation behind,” he said.

A smiling Calderon emerged from party offices to wave at supporters. He was scheduled to address the nation later Tuesday and meet with Fox on Wednesday.

Fox greeted the court’s decision with a smile during an appearance in Cancun, then publicly congratulated Calderon and invited Lopez Obrador to begin talks aimed at “strengthening the nation and our democracy.”

Markets, which had anticipated Tuesday’s ruling, were unchanged.

Tuesday’s ruling came two months, three days, and tens of thousands of pages of legal challenges after voters cast their ballots. The decision was unlikely to end the demonstrations that have crippled Mexico City’s center or to heal the nation’s growing political divide.

In the Zocalo plaza, thousands in a month-old protest camp chanted: “If there is no solution, there will be revolution!”