In an interview with The Washington Times, Mr. Nader, who is slated to speak at this weekend’s Green Festival in the District, also predicted a major shake-up in American politics by 2016 when a billionaire political messiah will be prepared to spend his own money to force choices in the next presidential election.

The consumer-advocate-turned-politician, who has run for president as the Green Party’s nominee and as an independent, called Republicans in Washington “cruel and ignorant.” But he saved his most biting barbs for Mr. Obama, who he said all but ignored fellow Democratic candidates at his nominating convention earlier this month.

“It’s the most politically selfish speech I’ve ever heard a candidate make in that he never mentioned congressional Democrats,” Mr. Nader said. “And it’s not just rhetoric. He doesn’t campaign with them.”