By Anthony Boadle
BRASILIA, April 14 (Reuters) - Eduardo Campos, a business-friendly socialist from Brazil's poor northeastern region, announced on Monday he will seek the presidency, vowing to restore confidence in the country's fiscal accounts and once booming economy.
The two-time governor of Pernambuco state picked as his running mate Marina Silva, a popular environmentalist who will bring millions of votes to the ticket. She will also draw the opposition of Brazil's wealthy agribusiness sector of which she is a declared enemy.
Campos, a youthful and charismatic politician, hopes to capitalize on growing discontent with the ruling Workers' Party that has been in power for 13 years by offering to preserve its social programs while providing more incentives for private investment.
Latin America's largest economy has slumped under President Dilma Rousseff. Standard & Poor's cut Brazil's credit rating last month by one notch to BBB-, the agency's lowest grade rating, citing slow growth and rising public debt.
"After three years, Brazil has come to a halt, the Brazilian people have lost hope, and the world has become disenchanted with us," Campos, 48, told a meeting of his Brazilian Socialist Party, which launched his nomination.
"Brazil's economic problems are mainly an issue of confidence and attitude. The world needs to see that Brazil has direction and transparency in its government accounts," he said.
Campos faces an uphill battle. He is running third in polls of voters' intentions, far behind Rousseff. But he has advanced closer to the main opposition leader, centrist Aécio Neves, since joining forces with Silva, a former presidential candidate who won 19 million votes in 2010.
A Datafolha poll in the first week of April showed support for Rousseff had dropped six percentage points to 38 percent since February, with Neves flat at 16 percent and Campos rising one point to 10 percent.
With inflation speeding up and the risk of anti-World Cup protests in June, these numbers could change swiftly when the election campaign gets off in earnest in July.
"If Rousseff enters a tailspin, Campos has potential to grow," said David Fleischer, a University of Brasilia politics professor who sees Campos' numbers rising when polls are based on electoral slates that include Silva's name.
While Campos announced his bid in the capital, Rousseff visited Pernambuco to grab headlines away from its former governor and highlight her government's financial backing for projects that made it one of Brazil's fastest-growing states.
Campos, the grandson of a beloved former governor of Pernambuco, has cozied up to the private sector, promising to reduce red tape and get government off their backs. He is expected to cut public spending to improve fiscal saving and try to lighten the heavy tax burden that businesses face in Brazil.
"It is easy to be business-friendly after Dilma, who ended up being totally unfriendly to business," said Andre Perfeito, chief economist at Gradual Investimentos. "Anyone else will be more palatable to markets."
The shares of state-run companies, which lost considerable market value as a result of Rousseff's interventionist policies, have gained on the Sao Paulo stock market in recent weeks on poll data that showed support for Rousseff was slipping.
If elected, middle-of-the-road Campos would not have much room to change macroeconomic policies, but he could achieve a lot by restoring credibility in long-term investment projects in Brazil, Perfeito said. (Reporting by Anthony Boadle; Editing by Jan Paschal)