Ralph Nader thinks he will be a factor in the presidential race again this year, but this time, he says, he is drawing votes from the Republican ticket.

He sparked the wrath of Democrats in 2000, when many said his third-party candidacy cost Al Gore the election.

He strongly disputes that notion — “There were 19 independent variables, and each one would have put Gore in the White House” he said in an interview today, citing the Supreme Court decision and Mr. Gore’s loss of his home state of Tennessee among them. And he called up The Caucus to boast that he seems to be draining votes from Senator John McCain, the Republican nominee, not Senator Barack Obama, the Democrat’s presidential candidate.

His evidence? He said polls show that when his name is added to the mix, Mr. McCain’s numbers go down. But those polls also include Bob Barr, the Libertarian candidate, so it is not clear who is taking votes from Mr. McCain. In addition, at least one recent poll shows that in a four-way race, Mr. Obama’s numbers drop from where they would be in a two-way race.

Mr. Nader also pointed to the fact that the Democrats are not trying to bump him off the ballot in various states, as they tried to in 2004.

“Last time, the Democrats filed 24 lawsuits in 18 states in 12 weeks to get us off the ballot,” he said, but this year, they have not filed any. He is now on the ballot in 45 states.

It is possible that no one has sued to remove Mr. Nader because they don’t think he will be a factor. While he won 2.7 percent of the popular vote in 2000, the closest election in modern history, he won just one-third of 1 percent in 2004.

But Mr. Nader says “it’s a very volatile year” and “you’re getting defectors from the whole spectrum of politics.”

He is trying to get included in the presidential debates, which start Friday, and is encouraging his supporters through his Web site (votenader.org) to call Mr. Obama’s campaign and say that having Mr. Nader in the debates “could help Senator Obama challenge the corporate Republicans.” (The site refers elsewhere to both parties as representing corporate interests.)

The commission on debates limits participation to candidates who have the support of at least 15 percent of voters in the polls; whatever support is being registered for Mr. Nader in a handful of states, it is nowhere near 15 percent.