By Anthony Boadle
BRASILIA, April 5 (Reuters) - Support for President Dilma Rousseff is slipping among Brazilian voters who are increasingly pessimistic about their country's economy and disappointed with her performance, according to a poll published on Saturday.
While Rousseff is still on track to win re-election outright in elections on Oct. 5, she has lost six points among potential voters since last month, a survey by local Datafolha polling firm said.
The poll showed more Brazilians want a change of course in government policies, and twice as many Brazilians think Rousseff's predecessor and mentor Luiz Inácio Lula da Silva is more qualified than her to carry out those changes.
The number of Brazilian intending to vote for Rousseff dropped to 38 percent from 44 percent in February, though her two potential rivals gained little or no ground. The leader of the main opposition party Aécio Neves was unchanged at 16 percent of voter intentions and Eduardo Campos, governor of Pernambuco state, edged forward one point to 10 percent.
The only candidate who could force a run-off vote against Rousseff is environmentalist and former presidential candidate Marina Silva, who is expected to run on Campos' ticket for vice president.
Latin America's largest economy is entering its fourth year of slow growth under Rousseff, who has lost the confidence of investors by failing to revive the economy or curb rising inflation in a context of deteriorating fiscal accounts.
Last month Standard and Poor's downgraded Brazil's credit rating to one notch inside investment grade, citing slow growth and rising debt.
Rousseff's dismal economic performance and the risk of losing the election have prompted calls within the ruling Workers' Party and governing coalition for the return of Lula, who is still Brazil's most influential politician, though he has indicated he is not interested in running again.
Asked who would be the best leader to carry out changes, 32 percent of those polled by Datafolha said Lula, with 17 percent picking Silva, his former environment minister, over 16 percent for Rousseff and 13 percent for Neves.
Rousseff survived massive street protests last year against poor public services, political corruption and the cost of building stadiums for the 2014 soccer World Cup. Recent polls show her popularity dipping again this year.
Datafolha said the approval rating for her government dropped 5 points since it previous poll at the end of February, with 36 percent of those polled agreeing that she is doing a good or very good job.
The number of Brazilians who believe Rousseff has achieved less than they had expected rose in April to 63 percent, from 41 percent a year ago, the poll said.
Rising inflation is major concern: 65 percent of those polled think it will get worse, up from 59 percent in February, according to the poll. It showed a growing number of Brazilians fear unemployment, which has remained low despite a sluggish economy, will also rise.
The Datafolha poll of 2,637 people published by the Folha de S.Paulo newspaper was carried out between April 2-3 and has a margin of error of two percentage points. (Reporting by Anthony Boadle; Editing by Lisa Shumaker)