Washington ? Ralph Nader on Sunday announced a fresh bid for the White House, criticizing the top contenders as too close to big business and dismissing the possibility that his third-party candidacy could tip the election to Republicans.

The longtime consumer advocate is still loathed by many Democrats who accuse him of costing Al Gore the 2000 election.

Nader said most people are disenchanted with the Democratic and Republican parties because of a prolonged Iraq war and a shaky economy. He also blamed tax and other corporate-friendly policies under the Bush administration that he said have left many lower- and middle-class people in debt.

“You take that framework of people feeling locked out, shut out, marginalized, disrespected,” he said. “You go from Iraq, to Palestine/Israel, from Enron to Wall Street, from Katrina to the bungling of the Bush administration, to the complicity of the Democrats in not stopping him on the war, stopping him on the tax cuts.”

Nader, who turns 74 later this week, announced his candidacy on NBC’s “Meet the Press.”

In a later interview with The Associated Press, he rejected the notion of himself as a spoiler candidate, saying the electorate will not vote for a “pro-war John McCain.” He also predicted his campaign would do better than in 2004, when he won just 0.3 percent of the vote as an independent.

“This time we’re ready for them,” said Nader of the Democratic Party lawsuits that kept him off the ballot in some states.

Democratic candidates Barack Obama and Hillary Rodham Clinton quickly sought to portray Nader’s announcement as having little impact. Republican Mike Huckabee welcomed Nader into the race.

Nader said Obama’s and Clinton’s lukewarm response was not surprising given that both political parties typically treat third-party candidates as “second-class citizens.”