Anti-government demonstrators began streaming into the streets of cities throughout Brazil on Sunday to demand the impeachment of President Dilma Rousseff.

It was the second such day of protests in less than a month and comes as polls show Rousseff entering the fourth month of her second term in office with historically low approval ratings.

Helicopter television images showed demonstrators, many of them dressed in the yellow and green colors of the Brazilian flag and brandishing placards reading "Dilma Out," congregating in the capital, Brasilia, in the northeastern cities of Salvador and Belem and in Belo Horizonte in central Brazil.

Demonstrations were expected later in Rio de Janeiro and in Brazil's economic capital, Sao Paulo, where more than 200,000 people turned out for the last round of demonstrations. The March 25 protest was among the biggest in Sao Paulo since demonstrations in 1984 demanding the end of the military dictatorship.

The protest movement has been organized, mostly via social media, by a motley assortment of groups. Most call for Rousseff's impeachment, but they are joined by others with demands ranging from a military coup to looser gun control laws. The groups say demonstrations were expected in as many as 400 towns and cities across this continent-sized nation.

The size of Sunday's turnout could determine the future of the campaign to impeach Rousseff, whose Workers' Party is embroiled in a massive corruption scandal at the state-run oil giant Petrobras. Many analysts say the movement could fizzle if organizers fail to deliver crowds as big as last month's.

A survey released Saturday by the Folha de S.Paulo daily found that 63 percent of Brazilians surveyed supported impeachment proceedings against Rousseff, while 33 percent opposed them. The same poll, by the respected Datafolha polling agency, showed Rousseff's approval ratings holding steady, with 13 percent of respondents giving her a great or good rating while 60 percent of respondents evaluated her performance as bad or terrible. The survey of 2,834 people in 171 municipalities was conducted on Thursday and Friday. It had a margin of error of plus or minus 2 percentage points.

While the kickback scheme at Petrobras, which prosecutors call the biggest corruption scandal ever uncovered in Brazil, is a focal point of anger against Rousseff, the president has also been beset by a spluttering economy, a rapidly depreciating currency and political infighting within the governing coalition and her own party.