Another coalition partner of Brazilian President Dilma Rousseff has announced it is quitting, dealing a further blow to her bid to stave off impeachment.
The Progressive Party (PP) said most of its 47 MPs would vote for Ms Rousseff to be impeached.
Last month the PMDB, the largest party in Brazil’s governing coalition, also voted to leave.
Ms Rousseff, who faces an impeachment vote in the lower house on Sunday, says her opponents of plotting a “coup”.
They claim she manipulated accounts to hide Brazil’s growing deficit ahead of her election campaign two years ago. She denies this and her supporters say the issue is not valid grounds for impeachment anyway.
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A PP spokeswoman told AFP news agency on Tuesday:”The party decided to withdraw from the… alliance, by majority decision.”
The PP is the fourth-largest party in the 513-seat lower house but it is not clear how its departure from the government might affect Sunday’s vote.
A two-thirds majority of 342 MPs is needed to send the impeachment case to the Senate.
A recent poll, before the PP’s announcement, showed 300 in favour of impeachment and 125 opposed, leaving 88 MPs still undecided or not stating their position.
Earlier on Tuesday, Ms Rousseff suggested that Vice-President Michel Temer was one of the ringleaders of the “coup” attempt against her.
She said a widely distributed audio message of Mr Temer appearing to accept replacing her as president, was evidence of the conspiracy. However, she did not identify him by name.
“They now are conspiring openly, in the light of day, to destabilise a legitimately elected president,” Ms Rousseff said.
She referred to “the chief and… the vice-chief” of the plot, an apparent reference to Mr Temer and lower house speaker Eduardo Cunha.
Brazil is “living in strange times”, she said, “times of a coup, of farce and betrayal”.
Mr Temer has said that the message was released by accident.
Speaking in an interview with the conservative Estado de Sao Paulo newspaper on Tuesday, Mr Temer argued that he had spent weeks away from the capital Brasilia specifically so that no-one could accuse him of plotting behind the scenes.
On Monday evening, amid rowdy scenes, a 65-member congressional committee voted 38 to 27 to recommend going ahead with impeachment proceedings.
MPs are due to start debating on Friday, officials said, with voting beginning on Sunday at about 14:00 (17:00 GMT). The result should be known later in the evening.
Security is expected to be stepped up around the Congress building in Brasilia as the vote takes place.
While President Rousseff’s opponents say the impeachment is supported by most Brazilians, the president’s supporters have labelled it a flagrant power grab by her political enemies.
If the president and Mr Temer are both suspended from office, the next in line to assume the presidency is Mr Cunha.
However, he is facing money-laundering and other charges.
513 members of the lower house of Congress
342 votes needed to move process to the Senate
41 senators out of 81 must vote in favour to begin impeachment trial
180 days she could be suspended for during the hearings
What happens next?
Lower house vote: An impeachment vote is expected in the lower house on Sunday. A two-thirds majority is required for it to go forward to the Senate. Latest surveys suggest the number in favour is short of the total needed to carry the motion.
Senate vote on trial: If Ms Rousseff case is sent to the Senate, a simple majority is enough to suspend her for up to 180 days while she is put on trial. Vice-President Michel Temer would step in during this period.
Impeachment vote: For Ms Rousseff to be removed from office permanently, two-thirds of the Senate would have to vote in favour. Mr Temer would remain president for an interim period should this happen.