BRASILIA,  (Reuters) – Brazil’s ruling party  candidate Dilma Rousseff has widened her lead in October’s  presidential race over opposition candidate Jose Serra, a poll  showed yesterday.

It is the biggest advantage any poll has so far given  Rousseff, who in December trailed former Sao Paulo state  governor Serra by as much as 20 percentage points.

Rousseff, a career civil servant from President Luiz Inacio  Lula da Silva’s Workers’ Party, got 41 percent of voter support  with 33 percent for Serra, according to the Vox Populi poll  released by TV Bandeirantes.

The same poll in June showed Rousseff ahead with 40 percent  support against 35 percent for Serra.

Former Environment Minister Marina Silva remained unchanged  with 8 percent.    Rousseff, Lula’s former chief of staff, has benefited from  the support of the most popular president in Brazil’s history  and breakneck economic expansion that is creating millions of  jobs this year.

“As more Brazilians realize she’s Lula’s candidate and  offers continuity, she rises in the polls,” said Christopher  Garman, Latin America analyst with EurasiaGroup consultancy in  Washington.

“It was a matter of time for Dilma to move ahead, I just  didn’t expect it to happen so soon,” Garman added.

A Datafolha poll expected to be published over the weekend  could confirm Rousseff’s advantage.

With only two and a half months left to the Oct. 3  election, investors are closely watching to see whether either  candidate can maintain a significant lead.

Over the past three months Rousseff and Serra have been in  a virtual tie, with poll results fluctuating in response to  their campaign advertisement on TV. Lula was campaigning late yesterday with Rousseff in  Pernambuco, the poor northeastern state where he was born.  Under Brazilian law public officials cannot use state resources  to campaign for candidates, but the former union leader argues  he is free to campaign after hours.