(Adds approval rating down, context)
By Anthony Boadle
BRASILIA, July 17 Support for Brazilian President Dilma Rousseff has slipped in the last two weeks and she is statistically tied with her main challenger in a second-round runoff, a poll released on Thursday showed.
Rousseff's support dropped to 36 percent among voters from 38 percent at the beginning of July, as Brazil prepares for elections in October, according to the Datafolha poll.
Support for Aécio Neves, the candidate for the pro-business PSDB opposition party, remained unchanged at 20 percent, the poll said, but in a simulation of a likely second-round vote, the gap between Rousseff and Neves narrowed to four percentage points, within the poll's margin of error.
Support for Eduardo Campos of the PSB party slipped to 8 percent from 9 percent two weeks ago, the poll said.
Rousseff's popularity has been hurt by high inflation in a stagnant economy and her support among voters has fallen from 47 percent in November, according to Datafolha polls that point to the tightest race since her Workers' Party won power in 2002.
The leftist president seeking a second term on Oct. 5 got a bump up in the previous Datafolha poll done at the start of July when Brazil was in the midst of the World Cup soccer tournament and Brazilians where excited by their team's chances.
Brazil suffered a humiliating quarter-final defeat at the hand of Germany that depressed the mood in the country.
Political analysts, however, say the soccer result will not affect the outcome of the elections as much as economic factors and the desire to see a government that will deal with the deficiencies in Brazil's public services.
Approval of Rousseff's government fell to 32 percent from 35 percent in the previous Datafolha poll on July 2.
Rousseff will campaign on her party's achievements in reducing poverty and raising millions of Brazilians into the modern consumer society. Opponent Neves will take her to task for excessive state intervention that has scared off investors and slowed a once-booming economy.
The poll broadcast on TV Globo's evening news program has a margin of error of two percentage points. Datafolha surveyed 5,377 eligible voters on Tuesday and Wednesday. (Reporting by Anthony Boadle; Editing by Ken Wills and Lisa Shumaker)