A rancorous Senate debate on the fate of President Dilma Rousseff dragged into a new day Thursday, with her critics arguing she caused deep damage to Latin America's largest nation while supporters called the effort to impeach her a coup d'etat.

The Senate's march toward a historic vote on impeaching Rousseff began Wednesday morning. The debate droned on through the day and into the wee hours of Thursday, with the vote possibly coming sometime around dawn.

"I'm asking for everybody's patience because we need to see this through to the end," Senate President Renan Calheiros said at one point.

Under the rules of the impeachment process, each senator was allowed up to 15 minutes to speak, and many made full use of their moment in the spotlight — despite admonishments by Calheiros for speakers to limit themselves to five to 10 minutes. That suggestion angered Rousseff's supporters, who said it was a bid to curb their freedom of speech.

Several thousand pro- and anti-government demonstrators gathered outside the Senate, each group kept on opposite sides of a wall erected down the middle of the lawn.

Small but intense clashes erupted between police and Rousseff supporters, with police using pepper spray and protesters throwing firecrackers. On the other side of the wall, a Carnival-esque spirit reigned, with pro-impeachment demonstrators sipping beer while decked out in the yellow and green colors of the Brazilian flag.

If a simple majority of the 81 senators voted in favor, Rousseff would be suspended from office and Vice President Michel Temer would take over for up to six months pending a Senate trial that could result in her permanent removal. That would require approval by two-third of the Senate, or 54 senators.

Polling by major newspapers indicated at least 50 senators were likely to vote in favor of impeachment. Some pro-impeachment senators said they expected as many as 60 such votes — a margin that would point to Rousseff facing a slim chance to emerge victorious from the trial and resume her mandate that ends in December 2018.

The effort to remove Rousseff originated in Congress' lower house, which delivered a resounding 367-137 vote in favor of impeachment last month.

While the impeachment measure was based on allegations that Brazil's first female president broke fiscal laws, the process morphed into something of a referendum on Rousseff and her handling of the country over the past six years.

Brazil is mired in the worst economic downturn in decades and a sprawling corruption scandal centered on the state-run Petrobras oil company has soured the national mood, even as the country gears up to host South America's first Olympic Games in August.

Supporters of impeachment blame Rousseff and her Workers' Party for the stalled economy and insist Temer, whose party has split from the governing coalition, represents the only hope of reviving it.

"To improve the life of the nation we need to remove them (Rousseff's Workers' Party) at this time," Sen. Magno Malta told a scrum of journalists outside the Senate floor. "We will start to breathe again and the doctor will say the nation has given signs of life and will be stable soon."

The Senate action came after the lower house voted 367-137 last month in favor of impeachment.

Polls have said a majority of Brazilians support impeaching Rousseff, though they also suggest the public is wary about those in the line of succession to take her place.

Temer has been implicated in the Petrobras corruption scheme as has Calheiros, the Senate head who is now No. 2 in the line of succession. Former House Speaker Eduardo Cunha, who had been second in line, was suspended from office this month over allegations of obstruction of justice and corruption.

Rousseff has vehemently denied her administration's financial sleight of hand moves constituted a crime and argued that such maneuvers were used by prior presidents without repercussions. She has stressed that unlike many of those who have pushed for impeachment, she does not face any allegations of personal corruption.

The impeachment process, Rousseff says, amounts to a "coup" aimed at undoing social programs that have lifted an estimated 35 million Brazilians out of grinding poverty over the past years.

Temer, of the centrist Democratic Movement Party, insists he would expand the popular social programs, though he has also signaled that fiscal rigor is needed to dig Brazil out of the current hole.

Adding to Brazilians' economic worries, the investigation into a multibillion-dollar kickback scheme at Petrobras has ensnared dozens of elite politicians and businessmen across the political spectrum. Although Rousseff herself hasn't been implicated, top officials in her party were and that tarnished her reputation.

The president "is having to pay for everything," Sen. Telmario Mota de Oliveira said, arguing that Brazil's problems shouldn't be all pinned on the president.

Analysts have said Rousseff also got herself into trouble with a prickly manner and perceived reticence to work with legislators that alienated possible allies. Rousseff, however, has suggested that sexism in the male-dominated Congress played a role in the impeachment.

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Associated Press writer Jenny Barchfield reported this story in Brasilia and AP writer Peter Prengaman reported from Buenos Aires, Argentina.