President Dilma Rousseff remains the clear favorite to win a second four-year term when Brazilians go to the polls in October, according to a survey released Tuesday.

The center-left incumbent leads likely main challenger Aecio Neves by a margin of 43.7 percent to 17 percent in the survey, which was carried out by pollster MDA for the National Transportation Confederation.

Socialist hopeful Eduardo Campos sits in third place, with just under 10 percent.

To date, none of those three candidates has formally expressed presidential aspirations, but Rousseff has already been proclaimed the candidate of the governing Workers Party.

Former President Luiz Inacio Lula da Silva, the main leader of the Workers Party and political mentor of the president, has said on more than one occasion that the party's main aim is her re-election on Oct. 5.

Also evaluated in the survey was the perception that voters have of the government, with its approval rating falling to 36.4 percent from 39 percent last November.

In contrast, Rousseff's personal approval rating stood at 55 percent, compared with the 41 percent who said they disapproved of her.

The survey was conducted Feb. 9-14 among 2,000 registered voters nationwide. It has an error margin of plus/minus 2.2 percent. EFE