President Luiz Inacio Lula da Silva wants Gomes to abandon his presidential ambitions, fearing he could drain votes from his anointed candidate, chief of staff Dilma Rousseff.

"Perhaps I could give President Lula's national project a modest boost by accepting this challenge," said Gomes in reference to running for the Sao Paulo governorship.

If Gomes drops out, the election would largely become a two-horse race between Rousseff of the center-left ruling Workers' Party and Sao Paulo state Governor Jose Serra of the centrist PSDB party.

Both are considered mainstream politicians who would adopt the market-friendly policies of Lula. Analysts say Gomes, a congressman of the center-left Brazilian Socialist Party, could pursue more leftist economic policies if he won.

Gomes has 11 percent of voter support, behind Rousseff with 25 percent and Serra with 36 percent, according to a survey by the Ibope polling firm published this month.

Former Environment Minister Marina Silva of the Green Party had 8 percent.

If Gomes drops out, Serra would pick up 5 percentage points, Rousseff 3 points and Silva 1 point, the poll showed.

Some analysts say Rousseff could benefit from fewer contenders because she would likely draw less criticism and could focus her attention on her main rival, Serra.

If no candidate wins more than 50 percent of the vote in the Oct. 3 poll, the top two finishers will face each other in a run-off vote on Oct. 31.

Rousseff might prefer to face Serra alone in the hope that the election will be more of a plebiscite on the hugely popular Lula's eight years in office.

Lula hopes voters will see Rousseff as signaling the continuity of his administration, during which the economy grew at its fastest in decades and millions of people emerged from poverty.