Pro-government senators argue with President of the Brazilian Senate Senator Renan Calheiros, center, during the session on the impeachment process against Brazil's President Dilma Rousseff, at the Federal Senate, in Brasilia, Brazil, Monday, May 9, 2016. The acting speaker of the lower house of Brazil's Congress on Monday annulled last month's vote on impeachment, delaying and complicating the process that was widely expected to see Rousseff suspended later this week. (AP Photo/Eraldo Peres)

RIO DE JANEIRO - The acting leader of the lower house of Congress has reversed a controversial decision that would have annulled a key vote in the impeachment process against President Dilma Rousseff, the interim speaker's spokesman said Tuesday.

Waldir Maranhao's annulment of the April 17 vote in the Chamber of Deputies plunged the impeachment process into uncertainty and sowed further discord among Brazil's fractious political class.

Maranhao's first move early Monday would have annulled the 367-137 vote to oust Rousseff, which sent the matter to the Senate for a possible trial of the president. The head of the Senate vowed to ignore Maranhao's decision and plow ahead with the process.

Marahnao's spokesman Marcos Alberto said the acting speaker reversed the decision just over 12 hours after his initial decision.

Such reversals are a staple of Brazilian politics, and the impeachment drama has been filled with such dramatic turns.

The decision clears the way for Wednesday's vote in the Senate on whether to accept the impeachment case against Rousseff and put her on trial for allegedly breaking fiscal rules in her management of the national budget. If a simple majority of senators decides in favour, Rousseff will be suspended and Vice-President Michel Temer will take over until a trial is conducted.

The impeachment proceedings come as Brazil is grappling with its worst recession in decades, a continuing corruption probe that already has ensnared top politicians and prominent businessmen, and an outbreak of the Zika virus. At the same time, the country's showcase city, Rio de Janeiro, is gearing up to host the Olympics in August.

Rousseff's once-overwhelming public support has eroded with the onslaught of bad news, with her approval ratings dipping into the single digits in recent months. While polls have suggested broad public support for her impeachment, they have also pointed to widespread worry about who might replace her.

Maranhao had argued that the lower house vote last month was riddled with irregularities, including party leaders telling members how to vote.

Speaking Monday, Maranhao said the vote was "We are not, nor will we ever be, joking around with how we make democracy."

Rousseff is battling impeachment over allegations that her government violated fiscal rules, in what critics say was a bid to artificially bolster the country's flagging economy. Rousseff has said that prior presidents used such fiscal manoeuvrs and that the impeachment effort amounts to a "coup" aimed at removing her and her left-leaning Workers' Party, which has governed the country for 13 years.

Rousseff reacted cautiously to Maranhao's initial announcement, suggesting it wasn't entirely clear what was happening.

"We have a difficult fight ahead of us," she said at an event about education. She also called for caution, saying that "we live in a time of cunning and wile."

Maranhao took over the reins in the Chamber of Deputies after former Speaker Eduardo Cunha, who was the driving force behind the impeachment effort, was suspended over corruption and obstruction of justice allegations against him.

The head of the Brazilian Order of Attorneys, Claudio Lamachia, said the organization "regards the decision with extreme worry."

"This sort of action responds to the momentary interests of certain political groups but ignores legitimate decisions that have already been made," Lamachia said in a statement.

The Eurasia Group, a U.S.-based political and economic risk consultancy, said in a statement: "The decision certainly took most observers by surprise, but we think it very unlikely to hold."

"But one way or another, the Supreme Court will most likely have to weigh in," it said.

News from © The Associated Press, 2016