Nader said in an appearance on NBC's "Meet the Press" neither Democrats nor Republicans are addressing the issues most important to Americans, including the Iraq war and corporate wrongdoing.

"You take that framework of people feeling locked out, shut out, marginalized and disrespected," Nader said. "You go from Iraq to Palestine to Israel, from Enron to Wall Street, from Katrina to the bumbling 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 ran for president as an independent in 2004 and as the Green Party candidate in 2000, added that if the Democrats "can't landslide the Republicans this year, they ought to just wrap up, close down, emerge in a different form."

Critics blame Nader for taking votes away from the Democratic Party nominee in 2000, Vice President Al Gore, and helping Republican George Bush to be elected.