* Rousseff lead unchanged, would win first round
* GDP growth to further boost Rousseff campaign
* Bank secrecy scandal apparently no impact on poll
By Raymond Colitt
BRASILIA, Sept 3 Brazil's ruling party candidate Dilma Rousseff held her lead in October's presidential race and would win in a first-round vote, an Ibope opinion poll showed on Friday.
Rousseff garnered 51 percent voter support against 27 percent for the main opposition candidate Jose Serra, according to the poll broadcast by TV Globo.
The result is unchanged from last week's Ibope poll, which showed Rousseff winning in the first round on Oct. 3 with 59 percent of the valid vote, once null and undecided votes are discarded as on election day.
TV Globo did not reveal the valid vote tally on Friday.
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Rousseff, President Luiz Inacio Lula da Silva's former chief of staff, has been cruising toward victory on the back of a booming economy and Lula's enormous popularity.
Her decisive surge came with the start of free TV advertisement last month, which gave many voters a closer look at the career civil servant who was little known until a few months ago.
She trailed Serra in some polls as recently as June.
Rousseff's campaign is likely to benefit further after official figures showed on Friday that the economy grew faster than analysts had expected [ID:nN03239813].
A brewing bank secrecy scandal, which Serra has been trying to pin on the ruling Workers' Party [ID:nN02224646], apparently had no impact on Rousseff's lead.
Rousseff is seen as continuing Lula's mostly market-friendly macroeconomic policies, which have ensured economic growth in recent years.
But she also intends to heighten the role of state companies in several key industries such as oil, banking and telecommunications.
While her 10-party governing coalition is expected to expand its majority in Congress, several analysts say her leadership ability will be put to the test by Brazil's notoriously undisciplined parties.
The Ibope survey polled 3,010 people between Aug. 31 and Sept. 2 and has a margin of error of plus or minus two percentage points. (Editing by Xavier Briand)