Members of the Brazilian Democratic Movement Party celebrate after announcing the party's withdrawal from President Dilma Rousseff's ruling coalition in Brasilia, Brazil, on Tuesday. Picture: REUTERS/GREGG NEWTON
Members of the Brazilian Democratic Movement Party celebrate after announcing the party's withdrawal from President Dilma Rousseff's ruling coalition in Brasilia, Brazil, on Tuesday. Picture: REUTERS/GREGG NEWTON

BRASÍLIA — Brazilian President Dilma Rousseff’s chances of surviving impeachment nosedived on Tuesday when her ruling coalition’s main partner jumped ship and went into opposition.

The Brazilian Democratic Movement Party (PMDB), the country’s largest party, voted to end its alliance with Ms Rousseff’s leftist Workers’ Party, or PT, immediately.

Ms Rousseff canceled a trip to a nuclear security summit in Washington later on Tuesday amid the political crisis.

Senator Romero Juca, the party vice-president, made the "historic" announcement after a rapid meeting on Tuesday. The meeting, broadcast live on national television, was the culmination of a long divorce with Ms Rousseff, leaving Brazil’s first female president grasping at straws as she tries to stay in power.

The vote and announcement took no more than three minutes and was accompanied by singing of the national anthem and shouts of "PT out!"

The split plunges Ms Rousseff’s government into crisis mode and, more seriously, greatly reduces her chances of mustering the one third of votes in the lower house of Congress that she needs to defeat a first impeachment vote expected in April.

"If you look at the numbers, that’s basically it," said Everaldo Moraes, a political science professor at Brasilia National University.

If the lower house votes in favor, an impeachment trial would start in the Senate, where a two-thirds vote would force Ms Rousseff from office.

PMDB head Michel Temer — who remains vice-president under Ms Rousseff despite the break-up — would take over as interim president.

Eliseu Padilha, a high-ranking PMDB member who served as minister of civil aviation in Ms Rousseff’s government, predicted that Ms Rousseff had only weeks left.

"In less than three months we’ll have a new government — in two months," he said.

Senator Aecio Neves, who heads the PSDB opposition party and who narrowly lost to Ms Rousseff when she won re-election in 2014, commented: "Dilma’s government is finished."

"The exit of the PMDB is the last nail in the coffin," he said.

The PMDB has 69 of the 513 lower house seats and 60 of these deputies will vote for impeachment, Mr Padilha said. Analysts say that the PMDB’s exit could also encourage minor coalition partners to quit.

Legislators from both the centre-right Progressive Party, which has 49 deputies, and the centre-left Social Democratic Party, which has 32, said their parties would meet this week on a possible split.

However, Workers’ Party loyalists are negotiating intensely with individual deputies, trying to persuade them to vote against the grain.

The impeachment case alleges that Ms Rousseff illegally borrowed money to boost public spending and mask the severity of the recession from voters during her re-election.

The Brazilian bar association filed a new impeachment petition Monday, seeking to expand the accusations to include allegations of involvement by Ms Rousseff in the multibillion-dollar corruption scandal centred on state oil company Petrobras.

Although still vice-president, Mr Temer, 75, increasingly resembles a politician preparing for power. He met on Monday with Mr Neves.

The growing instability has spilled onto the streets with millions of Brazilians marching against Ms Rousseff and smaller, but still vigorous, rallies held in her defence. Another round of pro-Rousseff protests was planned for Thursday.

Ms Rousseff has called on her mentor, former president Luiz Inacio Lula da Silva, to become chief of staff so that he could stiffen resolve in the ranks and put his negotiating skills to use.

But the move prompted a swift backlash from opponents who see the appointment as a bid to give Mr Lula da Silva ministerial immunity and protect him from corruption allegations related to the Petrobras probe.

The judge leading the probe controversially released a wire-tapped phone conversation between Ms Rousseff and Mr Lula da Silva that was interpreted as showing her giving him the post in order to shield him. Mr Lula da Silva has forcefully denied this and the wording of the conversation is ambiguous.

The full Supreme Court is expected to issue a definitive ruling on whether Lula can take up his appointment in the coming days.