By Paul Kane; Washington Post Staff Writer

Several Republican Party committees and candidates launched ads this week linking Democratic candidates to controversies surrounding Sen. Barack Obama, signaling one of the party's strategies should the Illinois senator secure the Democratic presidential nomination.

The North Carolina Republican Party yesterday unveiled a television ad showing Obama's former pastor, the Rev. Jeremiah A. Wright Jr., giving a sermon in which he says, "God damn America." The commercial's stated targets are the two leading Democratic gubernatorial candidates, who face off in a May 6 primary, on the same day as the state's presidential primary.

The candidates, Bev Perdue and Richard Moore, both have endorsed Obama. "They should know better. He's just too extreme for North Carolina," the narrator says in the ad.

Sen. John McCain (Ariz.), the presumptive Republican nominee, denounced the ad, and Obama suggested that it was up to McCain and the Republican National Committee to take it off the air.

"I assume that if John McCain thinks that it's an inappropriate ad that he can get them to pull it down since he's their nominee and standard-bearer," Obama told reporters while campaigning in Indiana.

State party officials declined to pull the ad, and late yesterday the party's Web site was still soliciting donations to keep the ad on the air.

In Louisiana, where Democrats have a rare chance to win a U.S. congressional seat vacated by a veteran Republican incumbent, the National Republican Congressional Committee came to the defense of its nominee Tuesday with an ad accusing state Rep. Donald J. Cazayoux Jr. (D) of backing tax increases and the "radical health-care agenda" supported by Obama.

"A vote for Don Cazayoux is a vote for Barack Obama and Nancy Pelosi," the narrator says, referring to the Democratic speaker of the House.

An independent conservative group, Freedom's Watch, is on the air in the Baton Rouge market with a similarly themed ad that pictures Cazayoux with Obama under the heading "big government scheme." The special election for that House seat is May 3.

In western Pennsylvania, a GOP challenger unveiled an ad on a campaign Web site accusing freshman Rep. Jason Altmire (D-Pa.) of defending Obama after he told donors in San Francisco that white working-class voters "cling" to gun rights and religion because they are "bitter."

"Barack Obama said our bitterness makes us cling to our religion, and our guns. This was simply an insult. But maybe the biggest insult of all is how Jason Altmire continues to defend Barack Obama," says Melissa Hart, the former representative who was ousted by Altmire in 2006 and faces a rematch this fall.