Dilma Roussef, candidate for the ruling Workers' Party (PT), is the hot favorite in Sunday's presidential elections and is widely predicted to become the nation's first female president.

Backed by outgoing popular President Luiz Inacio Lula da Silva, Rousseff, a former chief of staff of Lula, was predicted to win 55 percent of valid votes in the first round of the presidential elections, according to the most authoritative pollster CINI-IBOPE on Thursday.

Pollsters indicated that Rousseff had benefited from her close ties with Lula, who enjoys an approval rate of 80 percent. Some 93 percent of those polled by CNI identified Rousseff as Lula's candidate and nearly half tended to vote for someone who is close to Lula.

At the age of 62, Rousseff was born in the state of Minas Gerais to a middle class family consisting of a Bulgarian immigrant and a Brazilian.

He career is marked by activism against the 1964-1985 military dictatorship and work in the public service since the re-democratization.

In her youth, she participated in the armed resistance known as Colina (an acronym for Command of National Liberation) and VAR-Palmares (Armed Revolutionary Vanguard), fighting against the de facto regime.

She was imprisoned, tortured and spent three years in prison in the early 1970s.

In late years of the military regime, Rousseff fought for amnesty for citizens who had lost their civil rights and were persecuted by the government, and took part in the founding of Democratic Labor Party (PDT) in Brazil's southern region.

Close to important Brazilian political leaders, such as Leonel Brizola, she played a decisive role in the movement called Diretas Ja (Direct elections now), the hugest civil mobilization in Brazilian recent history culminating with the return of democracy.

After studying economics, she became in late 1980s secretary of mines and energy of the government of Rio Grande do Sul, which made her known in the whole country.

Affiliated with the Workers' Party since 2001, she was Minister of Energy during the first term of President Lula which began in January 2003, and in June 2005 she assumed the post of Chief of Staff.

During her tenure as chairman of the Board of Directors of the state-owned oil company Petrobras, Brazil reached self-sufficiency in oil production and mega reserves were discovered in the pre-salt layer of Brazil's seabed, which may turn the South American country into a large oil exporter.

Roussef was handpicked by president Lula himself to run for his succession and in April this year she left the post as chief of staff.

Divorced, she has a daughter who gave birth to her first grandson last month.

In 2009, Rousseff had to undergo treatment for a cancer in the lymphatic system, from which she recovered quickly.