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By Anthony Boadle
BRASILIA, June 19 (Reuters) - Brazilian President Dilma Rousseff's popularity has continued to fall, though the left-leaning leader is still favored to clinch re-election in a probable second round of vote, according to a new poll published on Thursday.
For the first time since massive protests broke out a year ago against inadequate public services and corruption, more Brazilian disapprove than approve of her government, including its signature poverty reduction policies.
The good news for the president is that she is holding her lead and her main rivals appear to have stopped advancing, though that could be because they are less well known to voters.
"The campaign will really take off in July, but this poll shows it will probably go to a runoff," said Renato da Fonseca, the head of polling at Brazil's National Industry Confederation, which commissioned the survey by the IBOPE polling institute. "If the vote were held today, she would certainly be re-elected."
Backing for Rousseff's re-election in October stands at 39 percent of eligible voters. Her main challenger Aecio Neves has the support of 21 percent, while Eduardo Campos has 10 percent.
The Rousseff government's approval rating has fallen to 31 percent from 36 percent in a previous IBOPE poll in March and is down to the same level as a year ago in the midst of protests. The president's personal approval rating dropped to 44 percent from 51 percent in the last poll.
Rousseff's popularity has been declining this year due to concerns about high inflation in a sluggish economy and investigations of mismanagement at the country's largest company, state-run oil firm Petroleo Brasileiro SA.
If the race goes to a runoff three weeks after the Oct. 5 vote, Rousseff would still win by 43 percent of the votes against Neves, of the centrist PSDB party, who would get 30 percent of the votes if the election were held today.
Campos, a former state governor and leader of the Brazilian Socialist Party, would get 27 percent of the votes in a runoff against 43 percent for Rousseff.
Rousseff, however, faces an uphill battle to convince Brazilians to give her a second term in office in the face of growing distrust in her stewardship of the nation.
Brazilians particularly disapprove of her handling of health and education services, rising crime and high taxation, according to IBOPE.
Worse, more Brazilians now disapprove of her policies in reducing poverty (53 percent versus 41 percent), the singular area of achievement by her Workers' Party since it was led to power a decade ago by labor leader Luiz Inacio Lula da Silva.
That could spell trouble for a president counting on the backing of Brazilians who most benefited from her social programs, estimated at a core 30 percent of the electorate.
The previous IBOPE poll commissioned by the CNI in March did not survey voter intentions. The new poll surveyed 2,002 people from June 13-15 and has a margin of error of plus or minus 2.0 percentage points. (Reporting by Anthony Boadle; Editing by Todd Benson, Chizu Nomiyama and W Simon)