Brazilian President Dilma Rousseff prepared Thursday to take the oath of office in Brasilia for her second term, beset by a huge corruption scandal and under pressure to restore economic credibility.

Thousands of supporters clad in party red gathered in the searing heat alongside pockets of detractors and visiting dignitaries, including US Vice President Joe Biden and 13 heads of state, ahead of Rousseff's arrival.

The 67-year-old former urban guerrilla will ride in an open-top Rolls Royce down the Ministries Esplanade to Congress where she will take the oath and receive the seals of office at 3:00 pm (1700 GMT), before heading to the presidential palace to make a national address.

Thereafter, Rousseff, the 200 million-strong South American giant's first female leader, is scheduled to preside a ceremony formally nominating her 39-strong new cabinet team.

Key amongst them is orthodox pro-market Finance Minister Joaquim Levy, tasked with galvanizing an economy which lumbered through left-wing Rousseff's first term.

Levy has already drawn up plans to make savings, including a reduction in unemployment insurance.

Economic growth, forecast to come in barely above zero in 2014, has slumped badly compared with 2010's heady heights of 7.5 percent under Rousseff's Workers Party predecessor Luiz Inacio Lula da Silva.

The world's seventh-biggest economy boomed for a time under Silva, who put in place a decade ago the extensive welfare programs which helped secure Rousseff's narrow poll win in October over Social Democrat and business world favorite Aecio Neves.

A rare bright spot on the economy is that the official jobless rate in November stood at a record low of 4.8 percent.

Rousseff's second term also starts with her government dogged by scandal amid a legal probe into a huge network of corruption at Petrobras, the state oil firm she used to chair.

The scandal and ongoing police investigation -- dubbed "Operation Car Wash" -- erupted just months before Rousseff won re-election, but failed to derail her campaign.

So far suspicion has fallen on 39 people, including former Petrobras directors and pro-government politicians, a network which allegedly laundered around $3.8 billion creamed off from inflated contracts.

Rousseff says she will leave "no stone unturned" with regard to the probe, while giving a vote of confidence to Petrobras head and ally Graca Foster.

Political analyst David Fleischer of Brasilia University told AFP that "the Petrobras scandal is part of the problem of trying to restore confidence in Brazil," adding to the equally tough challenge of reviving economic growth.

Among Rousseff's other first-term challenges were unprecedented mass street demonstrations ahead of last year's football World Cup.

And Rousseff's efforts to reward allies in a nine party-strong coalition have engendered some criticism, including over the choice of a controversial evangelical pastor, George Hilton, for the sports portfolio a year and a half before Rio stages South America's first Olympics.

Hilton, who will oversee the organization of the 2016 Games, was arrested eight years ago in possession of some $220,000 in banknotes which allegedly comprised donations from his congregation.