Sao Paulo, Brazil (CNN) -- A week after the death of Brazilian presidential candidate Eduardo Campos in a plane accident, his running mate Marina Silva announced she would replace him on the ticket, setting the stage for a tighter race.
The announcement was widely expected, and a poll released Monday showed that Silva, a well-known environmentalist, had a better chance of defeating President Dilma Rousseff in the Oct. 5 elections than Campos would have.
After a lengthy meeting with members of Campos' Brazilian Socialist Party (PSB), Silva, a former senator and environmental minister, was applauded and cheered at a news conference in Brasilia.
"Without Eduardo we have what always united us: the awareness of where we want to go together," she said.
Campos was polling a distant third before his death last Wednesday.
The latest figures from the survey group Datafolha showed Rousseff still in the lead with 36% of the vote. But Silva was in second place with 21%, while the center-right candidate Aecio Neves had slipped to third with 20%.
That would mean a run-off vote in which, according to the poll, Silva would garner 47% of the ballots, compared with 43% for Rousseff.
While the figures likely reflect a sympathy vote following Campos' tragic accident, the numbers are worrying for the governing Workers Party.
At the news conference on Wednesday, the PSB also announced that Congressman Beto Albuquerque would be Silva's running mate. Silva unsuccessfully ran for president in 2010 for the country's Green Party.
She told the crowd Wednesday that she arrived with "a sense of responsibility, of commitment assumed during the last 10 months of intense work, ready to honor the commitment and go forward with all of those that were building a project with Eduardo."