SAO PAULO/BRASILIA — Protesters poured en masse onto the streets of Brazil’s major cities on Sunday to demand the removal of President Dilma Rousseff, raising the stakes for the leftist leader as she struggles to pull the country out of its worst political and economic crisis in a generation. The demonstrations were the latest in a wave of anti-government rallies that lost momentum late last year but has gained strength as a sweeping corruption investigation nears Rousseff’s inner circle. The magnitude of Sunday’s protests could be crucial in persuading a divided Congress to back ongoing impeachment proceedings against Rousseff.

No official estimates for the number of protesters across Brazil were immediately available. But two government sources, speaking on condition of anonymity, told Reuters the demonstrations could be bigger than anti-government rallies in March 2015, which gathered as many as 1 million people.

The demonstrations were peaceful, with tens of thousands wearing the national yellow and green colors and holding banners that read “Dilma out” and “Stop with corruption.”

“I support her impeachment and new elections because the presidential vote in 2014 was financed with dirty money from corruption,” said Alexandre Cortes, a 39-year-old engineer draped in a Brazilian flag in a festive rally in Sao Paulo, the country’s biggest city and financial capital.

Many blame Rousseff for sinking the economy into its worst recession in at least 25 years. Opinion polls show that more than half of Brazilians favor the impeachment of the president, who was re-elected by a slim margin for a second four-year term in 2014.

Rousseff is the latest leftist leader in Latin America to face social upheaval as a decade-long commodities boom that fueled breakneck growth rates comes to an abrupt end.

Ahead of the demonstrations, tensions were high after Sao Paulo state prosecutors requested the arrest of Rousseff’s political mentor and predecessor, Luiz Inacio Lula da Silva, on money-laundering charges. A judge still has to decide on the request, which can be rejected.

As in previous protests, Sunday’s rallies were led by middle-class Brazilians angry over growing allegations of corruption in Rousseff’s administration.

Image: Demonstrators take part in a protest to demand the resignation of Brazilian President Dilma Rousseff
Demonstrators take part in a protest to demand the resignation of Brazilian President Dilma Rousseff, on March 13, 2016 in Paulista Avenue in Sao Paulo. Miguel Schincariol / AFP – Getty Images

The poor Brazilians who form the traditional base of her ruling Workers’ Party have not turned out in great numbers at the recent protests, but their support has faded as the recession has deepened and inflation has climbed.

“This government helped many people buy homes, cars and electronics, but we still don’t have health, education and basic sewage,” said Paulo Santos, a waiter who stopped at the demonstration in Rio de Janeiro before heading to work.

In the capital, Brasilia, protesters inflated a giant doll of Lula wearing a striped prison uniform and chained to a ball that read “Operation Carwash,” the name of the investigation centered on state oil company Petrobras. Police estimated about 100,000 protesters in Brasilia alone.

A few hundred government supporters wearing red shirts and holding banners that read “There will not be a coup” stood outside Lula’s home on the outskirts of Sao Paulo.

The probe has implicated senior politicians from Rousseff’s coalition as well as top business executives.

Popular discontent grew in recent weeks after a ruling party lawmaker reportedly testified under a plea bargain and accused Rousseff and Lula of trying to hamper the Petrobras investigation.

The two-year-old probe has strained Rousseff’s ties with her main coalition partner, the Brazilian Democratic Movement Party (PMDB). At its national convention on Saturday, the PMDB threatened to break with her government and join the opposition.

Brazilian shares and its real currency have surged in recent weeks as investors bet that a change in government would lift business and consumer confidence and rescue an economy that contracted 3.8 percent last year.

Rousseff, whose popularity is near record lows, has said she will not quit and blamed her opponents for creating the crisis that is sinking the economy.

Political tensions have stalled Rousseff’s legislative agenda, which included measures to limit public spending and overhaul a costly pension system to regain investors’ trust.