Mr Ralph Nader, whose third-party White House bid in 2000 was blamed by some Democrats for helping elect President George W. Bush, said today he will try again this year as an independent.
Ignoring the pleas of Democrats to stay out of the race, the veteran consumer advocate said he wanted to challenge the stranglehold on the political process of the two main parties and fight their addiction to corporate interests.
"Washington is corporate-occupied territory, and the two parties are ferociously competing to see who is going to go to the White House and take orders from their corporate paymasters," Mr Nader said on NBC's Meet the Press.
Mr Nader's Green Party bid picked up nearly 2.9 million votes in 2000 and was blamed for siphoning support from Democrat Al Gore - particularly in Florida, where Mr Nader won 97,488 votes and Mr Gore's loss by a bitterly contested 537 votes cost him the presidency.
Mr Nader started an exploratory committee late last year to raise money for a presidential run. He had ruled out another bid for the Green Party, which was split on his candidacy and will not pick its nominee until this summer.
"I've decided to run as an independent candidate for president," he said.
A public opinion poll in October found two-thirds of Americans did not want Mr Nader to run again, and Democrats from across the ideological spectrum have asked him to stay out of the race and give them a clear shot at Mr Bush.
Democratic presidential front-runner Mr John Kerry told reporters on Saturday night he was not afraid that a Nader candidacy would hurt his potential challenge to Mr Bush. "I think my campaign is speaking to a lot of the issues Ralph Nader is concerned about," Mr Kerry said in Atlanta, Georgia.