Longtime Republican strategist Charlie Black said the Vilsack-King race could be a factor for Obama, but that the presidential race usually drives turnout.
"There could be isolated examples, like the Steve King example, where a congressional race drives turnout, and the top of the ticket benefits. But there wouldn't be many," said Black, who has advised GOP candidates for more than 30 years.
King is seeking a sixth term in a district slightly less favorable than the one he has represented for almost 10 years, a change that followed the redrawing of congressional district lines after the 2010 census.
Republicans in King's new 4th District still hold a 46,000-voter registration edge over Democrats. McCain won the counties that make up the new district with 54 percent of the vote, while Bush got 55 percent.
Christie Vilsack, who could become the first woman Iowa sends to Congress, says she isn't running to drive turnout for Obama.
"I don't see it as an uphill climb. I'm pretty competitive and I want to win," she told The Associated Press. "I'm not thinking that much about the national level."
Last year, Vilsack relocated to Ames, a college town in the southeast corner of the newly drawn district in central Iowa. The rest of the 39-county district is a vast expanse of farms, small cities and towns with a struggling manufacturing base but growing renewable fuel sector.
At 61, she has spent most of her life in Mount Pleasant near the state's farthest southeast corner, more than 150 miles from her new home. She became a statewide figure and traveled to the state's small towns promoting public libraries and literacy during her husband's eight years as governor.
King's old district includes 19 counties in Iowa's furthest northwest corner, the state's GOP epicenter. Vilsack is counting on over-performing in the 20 counties where both would be new names on the ballot, especially with the district's nominal plurality of independent voters.
Vilsack has recruited a top-flight team led by seasoned native Iowa strategist Jessica Vanden Berg, who has managed winning U.S. Senate races in Minnesota and Virginia. She also has at her disposal a core of loyal Iowa and national strategists from her husband's campaigns, including his brief bid for the 2008 presidential nomination.
King already has shown signs of taking Vilsack more seriously than past Democratic opponents, whom he defeated on average by more than 25 percentage points.
For the first time, King has reached beyond a cadre of loyal aides, enlisting as his campaign manager Jake Ketzner, a top aide on Terry Branstad's winning comeback campaign for governor in 2010. He plans to direct his campaign from an office in Ames, another first for a candidate who has kept his campaign headquarters in his small hometown of Early.
King is also engaging Vilsack at this early stage. He has agreed to debate her — another first — and has begun critiquing her, specifically accusing her of avoiding taking a position on Obama's signature legislation, the 2010 health care bill.
King supports repealing the bill. Vilsack said she supports aspects of it but stopped short of saying whether she would have supported it or whether she supports its central provision of requiring all Americans to obtain health insurance.