Independent presidential candidate Ralph Nader is crashing the Republican National Convention, stopping by Madison Square Garden, giving a flurry of media interviews and offering a running critique of nearly every major policy initiative of the Bush administration.

President Bush "has plunged our nation into a war that was unconstitutional from the get-go -- a war that was premised on false pretenses, on a platform of fabrications and lies," Nader said Wednesday, reiterating his call for the president's impeachment. He criticized the administration's support for free trade agreements, accused it of "coddling" the Chinese government and mocked the Republicans' efforts to put a moderate face on its convention.

"This corrupt Republican Party that has the brazenness to headline its day yesterday 'People of Compassion,' " he said. "Where are you, George Orwell?"

Democrats turned down Nader's request to attend their convention in Boston last month, and the Republicans did not bother to respond to his request. So Nader turned up uninvited at the Republicans' convention to assail the president's policies, promote his own agenda and seek media attention for something other than his uphill drive to get his name on state ballots.

On Wednesday, election officials in Oregon rejected Nader's bid to get on the state's November ballot, citing irregularities in the candidate's petitions. Meanwhile, a court in Michigan ruled that the longtime consumer advocate could not run there under the Reform Party's banner, forcing him, at least for now, to depend on a Republican-backed signature campaign to put him on the ballot as an independent. Nader's campaign vowed to fight both decisions in court.

On Tuesday, Nader wandered in the halls of the arena for several hours, giving interviews and handing out anti-Bush literature. From there he went to Columbia University, where he spoke against the Iraq war. After a closed-door fundraiser and another round of interviews, he was off to Wall Street, where his campaign unfurled a large banner demanding Bush's impeachment.

Nader lauded the thousands of protesters who have taken to the streets of this city, saying their efforts reflect their frustration with the news media. "They represent millions of people -- workers, consumers, environmentalists, poor people. They should regularly be on television," he said. "They feel like they're shut out, and so the only way they can express themselves is on the streets." He said he did not personally participate in any protests, saying he was focused on his ballot drive.

Nader said he prefers Democrat John F. Kerry to the president -- and focused most of his fire on Bush. But he mocked Kerry's political consultants, calling them "losers" who are making the candidate too cautious.

Third-party presidential candidate Ralph Nader, right, talks to Jon Snow of Britain's Channel 4 at Madison Square Garden, site of the Republican National Convention.