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Barack Obama is becoming a more familiar face for TV viewers in Mississippi and Louisiana, but not by choice; instead, the Illinois senator is the focal point of several new commercials being run by Republican groups ahead of special elections to be held in both states in early May.

Whereas Hillary Rodham Clinton was once considered the Democrat that Republicans would most like to see at the top of the ticket in November, Obama's "bitter" comments and his association with the Rev. Jeremiah Wright have helped make him more vulnerable to attack from the right. Now Republicans are using Obama's missteps to target downballot candidates.

In Mississippi's First District, Southaven Mayor Greg Davis (R) is facing off against Democratic businessman Travis Childers in a runoff to replace Rep. Roger Wicker (R), who moved to the Senate after Trent Lott's resignation. While the seat had been considered safe for the GOP, Childers shocked pundits by coming within 400 votes of capturing it in the first round of voting on April 22. Now, the National Republican Congressional Committee and Davis are going on the offense, launching negative ads that link Childers to Obama, John Kerry and Nancy Pelosi.

Davis' new ad notes that Childers has been endorsed by Obama, then references Wright and "Bittergate" in order to portray Childers as a liberal whose values are not in line with Mississippi voters. "Obama says Childers will put progress before politics. But when Obama's pastor cursed America, blaming us for 9/11, Childers said nothing," an announcer charges as Childers is shown alongside Wright. "He took Obama's endorsement over our conservative values." The NRCC ad, meanwhile, takes pains to highlight the fact that National Journal ranked Obama the most liberal senator in its 2007 vote ratings.

The Louisiana Sixth District is home to another special election fight, this one between Republican Woody Jenkins and Democrat Don Cazayoux. Last week, the NRCC and conservative advocacy group Freedom's Watch jumped into the debate, launching TV spots linking Cazayoux to Obama's health care agenda.

The NRCC claims that if Cazayoux's candidacy came with a warning label, "it would say a vote for Don Cazayoux is a vote for Barack Obama and Nancy Pelosi." Nicknaming the Democratic candidate Don "Tax You," announcers accuse Cazayoux of supporting "Obama's radical agenda on health care" and say that if elected, "he'll do what [Obama and Pelosi] tell him to do."

Freedom's Watch takes up the Obama health care plan in more detail, claiming it will cost "up to $65 billion" but "still would leave millions without coverage." The ad labels the plan a "big government scheme" and encourages voters to "tell Don Cazayoux raising taxes and more bureaucrats won’t heal our health care system." A nonprofit formed in 2007 to counter liberal groups such as MoveOn.org, Freedom's Watch plans to spend heavily on downballot races in 2008.

Perhaps in a preview of what's still to come if Obama becomes the nominee, the National Republican Senatorial Committee has also crafted web ads linking several prominent Democratic candidates for the Senate -- including Reps. Mark Udall of Colorado and Tom Udall of New Mexico, as well as Louisiana Sen. Mary Landrieu -- to the Illinois senator.