WASHINGTON — Democrat Barack Obama's campaign said Thursday that Michelle Obama never used the word "whitey" in a speech from the church pulpit as he launched a Web site to debunk rumors about his campaign.

The rumor that Michelle Obama railed against "whitey" in a diatribe at Chicago's Trinity United Church of Christ has circulated on conservative Republican blogs for weeks and was repeated by radio talk show host Rush Limbaugh. The rumor included claims of a videotape of the speech that would be used to bring down Obama's candidacy this fall.

"No such tape exists," the campaign responds on the site, www.fightthesmears.com. "Michelle Obama has not spoken from the pulpit at Trinity and has not used that word."

The Obamas recently resigned from Trinity, where the Rev. Jeremiah Wright was the longtime pastor. Wright came under fire for sermons in which he cursed America and accused the government of conspiring against blacks. Video of the sermons spread quickly on the Internet and threatened great damage to Obama's campaign.

Other false claims about the Illinois senator —that he's secretly a Muslim who refuses to say the Pledge of Allegiance and is intent on destroying America — spread widely during the primary campaign, and the candidate made it a habit of telling audiences to respond to e-mail rumors to set the record straight.

Campaign officials realized they needed to step up their debunking efforts for the general election, when many voters who aren't familiar with the freshman senator will be learning more about him.

Barack Obama bristled when a reporter asked him about the "whitey" rumor on his campaign plane last Thursday, saying it was nonsense that shouldn't be repeated in questioning by a mainstream reporter.

"It is a destructive aspect of our politics right now," Obama told journalists. "And simply because something appears in an e-mail, that should lend it no more credence than if you heard it on the corner. And you know, presumably the job of the press is to not go around and spread scurrilous rumors like this until there's actually anything, one iota of substance or evidence that would substantiate it."

At the same time, his campaign was preparing the site to help stop lies that are spreading online.

The site explains that Obama is "a committed Christian" who never attended a radical madrassa during his childhood in Indonesia. With chain e-mails falsely claiming Obama was sworn into the Senate on the Koran, the central religious text of Islam, the Web site includes a photo showing him taking his oath of office on the family bible.

It shows C-SPAN video of Obama leading the Pledge of Allegiance with his hand over his heart as he presided over the Senate on June 21, 2007. It encourages people to give the campaign their e-mail addresses to "spread the truth."