BRASÍLIA - The fight to oust Brazil's President Dilma Rousseff speeded up on Monday after lawmakers authorized impeachment proceedings against her, deepening the country's political crisis.

Opponents of the 68-year-old leftist leader said they would quickly go to the Senate to formally hand over the impeachment case, following Sunday's overwhelming approval in the lower house.

The Senate is expected to vote in May on whether to open a trial, at which point Rousseff would have to step aside, with her vice president taking over. A two thirds majority in the Senate would then force her from office.

"Impeachment!" was the celebratory front-page headline of Folha de Sao Paulo daily on Monday. "Close to the end," said another leading newspaper, O Globo, adding: "Dilma Rousseff yesterday started to say goodbye to the presidency of Brazil."

The marathon vote on Sunday saw 367 of the 513 deputies in the lower house of Congress back impeachment, well over the two thirds majority needed to move the case forward.

Cheering and confetti burst from opposition ranks when the vote passed, countered by jeering from Rousseff allies - a snapshot of the divisive mood consuming the country just four months before Rio de Janeiro hosts the Olympics.

Rousseff is accused of illegally manipulating budget figures. But Rousseff's attorney general, Jose Eduardo Cardozo said the charges were flimsy and amounted to "a coup against democracy."

Rousseff was to give her first public reaction on Monday, he said.

Carla Selman, an analyst at IHS Country Risk, a consultancy, said that events could move quickly given the decisive nature of the lower house vote. "This is likely to accelerate a vote in the Senate, where the pro-impeachment camp is also expected to win," Selman said.

Financial markets have been betting heavily on Rousseff's exit and the advent of a more business-friendly government to kickstart Brazil's economy.

The country is in the grip of its worst recession for decades and political paralysis in the capital has prevented reforms that might attract back foreign investors, scared off by Brazil's junk credit ratings.

But the expected euphoric reaction at market opening on Monday did not materialize after being outweighed by the dampening effect of tumbling world oil prices.

If, as many expect, the Senate goes on to start a trial, Vice President Michel Temer, who abandoned Rousseff to become a key opponent, will assume power. He would also stay on if the trial ended in impeachment.

Monday's newspapers printed pictures of him smiling as he watched the vote. But the celebrations could be short lived, analysts say.

Temer would inherit a country wallowing in economic disarray and a dysfunctional political scene where Rousseff's Workers' Party vows revenge. "It will not be easy" for Temer, said Andre Cesar, an independent political analyst. "It will be a nightmare."

Analysts predict a long crisis rather than the radical fix that proponents of impeachment say would follow Rousseff's ouster.

Rousseff allies say the president would fight to the end against what they see as a bid by the opposition defeated in 2014 elections to take power by other means.

"The coup plotters have won here in the house," said Jose Guimaraes, leader of the Workers' Party in the lower house of Congress.

The government "recognizes this temporary defeat but that does not mean that the war is over," Guimaraes said. "The fight will continue in the streets and in the Senate."

Cardozo described Rousseff, who was imprisoned and tortured under military rule in the 1970s, as "very strong" and able "to fight a good fight." Huge opposition rallies over recent months have played a big role in turning pressure against Rousseff into an unstoppable avalanche. Now anger on the streets could again play a role as the stakes in the crisis rise even higher.

Sylvio Costa, who heads the specialist politics website Congresso en Foco, told AFP that Brazil's troubles are only starting. "Whoever loses will keep protesting in the streets," he said. "What's certain is that the crisis will not end today."