Brazilian President Dilma Rousseff has branded her vice president a traitor and said he was a conspirator in a "coup" using impeachment proceedings to bring down a popularly elected government.
"If there were any doubts about my denunciation that a coup is under way, there can't be now. The coup plotters have a leader and a deputy leader," she said in a blistering attack in the capital Brasilia on Tuesday.
Referring to the leak on Monday of a recording in which her vice president, Michel Temer, practises the speech he would make if Rousseff were impeached, the president said: "The mask of the conspirators has fallen."
"We are living in strange and worrying times, times of a coup and pretending and treachery," she said.
"Yesterday they used the pretence of a leak to give the order for the conspiracy."
In a ruthless and complex contest, supporters and opponents of Brazil's first female president raced to amass the votes that will either send her to trial in the Senate or torpedo the procedure.
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After a congressional committee voted to recommend Rousseff's removal from office in chaotic and bad-tempered scenes late on Monday, the stage was set for this weekend's showdown.
On Tuesday, the controversial speaker of the lower house of Congress, Eduardo Cunha, was expected to present the formal impeachment document to the chamber. Deputies were then due to start debating on Friday with a vote pencilled in for Sunday.
"Yesterday it became clear that there are two leaders of the coup who work together in a premeditated way," Rousseff said without giving names, although the context clearly referred to Temer and Cunha.
"They are coup plotters, without respect for democracy," she said. "They are trying to bring down without legal justification a president elected with 54 million votes."
Rousseff faces impeachment proceedings over allegations that she illegally manipulated government accounts to cover up the depth of budget woes.
The lower house of Congress was to vote on the impeachment at the end of this week. If an impeachment trial then starts in the Senate, Temer would take over as president and if she is impeached, he would remain in power.
Opponents of Rousseff deny her frequent claims of a coup plot. Rousseff is hugely unpopular as Brazil sinks into its worst recession in decades.
The latest survey of the 513 deputies in the lower house by the daily newspaper Estadao on Monday showed 299 favouring impeachment and 123 opposed. That left the result in the hands of the 91 deputies still undecided or not stating a position.