Women protest against the impeachment of President Dilma Rousseff at Paulista avenue in Sao Paulo, Brazil, May 11, 2016. [Photo/Agencies]

BRASILIA - Supporters of Brazilian President Dilma Rousseff clashed with police outside the Senate on Wednesday ahead of a vote to put her on trial for breaking budget laws, that would mark the end of 13 years of leftist rule in Latin America's biggest country.

If her opponents garner a simple majority in the 81-seat Senate, in a session that will last late into the night, Rousseff will be replaced on Thursday by Vice President Michel Temer as acting president for up to six months during the trial.

After speeches by half of the 70 senators who had registered to speak, 27 had indicated they would vote to put Rousseff ontrial, versus only seven against.

Outside Congress, where a metal fence was erected to keepapart rival protests, about 6,000 backers of impeachment chanted "Out with Dilma" while police used pepper spray to disperse gangs of Rousseff supporters, who hurled flares back. One person was arrested for inciting violence.