RIO DE JANEIRO (Reuters) - Brazil's President Dilma Rousseff and environmentalist Marina Silva would be tied in the first round of elections on Oct. 5, a poll suggested on Saturday, as a meteoric rise in support for Silva showed signs of plateauing.
The survey by polling firm Sensus showed Rousseff would get 29.8 percent in the first round of the vote, with Silva on 29.5 percent.
Silva is still shown winning a likely runoff, taking 47.6 percent of the vote against Rousseff's 32.8 percent, according to the survey.
Two other polls published this week showed Silva's dramatic rise in the polls has leveled out and Rousseff has gained some ground.
Analysts said the polls appeared to show the novelty of Silva's candidacy and the outpouring of sympathy over the death of her party's original candidate in a plane crash had begun to wane.
Revisions to her proposals, including the withdrawal of a commitment to back gay marriage after evangelical pastors denounced her, has also lost Silva some points among her core urban middle-class supporters.
Three weeks after Silva was thrust into the race, Rousseff has taken off the gloves and begun to attack her rival, painting her as a wild card whose policies would cause layoffs and undo social gains made under the ruling Workers' Party.
Silva's rejection rate - the proportion of voters who said they would never vote for her - was 22.3 percent, well below Rousseff's 44.3 percent, but substantially higher than previous polls. On Wednesday surveying firm Ibope had put Silva's rejection rate at 12 percent.
Third-placed candidate Aecio Neves would take 15.2 percent of the first round vote, according to the poll.
Sensus said 2,000 people across the country took part in the poll between Sept. 1-5.
(This story corrects date of election in lede)
Reporting by Stephen Eisenhammer; Editing by Andrew Heavens