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

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 site is a response to the realities of a brave new world, where information travels 24 hours a day on blogs and voters are increasingly turning to the Internet for information. It's a particular problem for Obama, a relative newcomer to national politics who is still unknown to many voters and has been the target of persistent misinformation campaigns online.

In another sign of the campaign moving into the general election race, the Democratic National Committee's spokeswoman said yesterday its political and field operations are relocating to Chicago, where Obama's campaign is based. While other departments will remain in Washington, it's an effort to streamline the campaign and party efforts in one strategy instead of the overlapping efforts of past presidential elections.

E-mails about Obama rank No. 2 on the list of "Hottest Urban Legends" on snopes.com, an Internet rumor-debunking site, behind e-mail greeting cards that could expose computers to viruses.

Michelle Obama has often been the target of conservative attacks, prompting Obama to demand his rivals, "lay off my wife." Much of the criticism came from her comment that her husband's campaign has made her proud of her country "for the first time," a remark that inspired a Tennessee Republican Party Web video questioning her patriotism.

There also have been more insulting attacks, and not limited to the Internet.

Fox News Channel referred to Michelle Obama as "Obama's baby mama" in a graphic on Wednesday, using the slang description of a woman who has a baby outside of a romantic relationship or marriage. Fox anchor E.D. Hill also referred to it as a "terrorist fist jab" when the Obamas bumped knuckles on the night he clinched the nomination. Hill has apologized.

The Obamas 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.