Iowa's Republican Senator Chuck Grassley, the top Republican on the Senate Finance Committee and one of the leading opponents of healthcare reform, has never faced a serious reelection challenge since he first rode Ronald Reagan's coattails to the Senate in 1980. Next year may be different.

Christie Vilsack, the wife of former Iowa Governor Tom Vilsack, sounds as if she may be the "mystery candidate" the chairman of the Iowa Democratic Party said was poised to run for the U.S. Senate.

Republican Chuck Grassley will seek a sixth term in the U.S. Senate in 2010 and, so far, two eastern Iowa Democrats who once served in the state legislature have announced they're running.  But during an interview with WHO TV, Christie Vilsack -- a lifelong Democrat -- revealed she's considering a run for the senate herself.

"I am honored that people would think of me in that way and would talk to me about running for any office and I think I'm well-qualified to run," Vilsack said.  "I think I'm qualified to serve, so time will tell."

As desmoinesdem has already noted here at MyDD, Grassley has been hemorrhaging support in recent months as voter in his state have watched him serve as one of the leading obstructionists attempting to block healthcare reform. As you can see from the chart of SurveyUSA polling below, Grassley has gone from an impressive 71 percent positive/23 percent negative approval spread in February to a much more lukewarm 50 percent positive/40 percent negative spread.

That trajectory is simply awful for Grassley, and it speaks to his vulnerability to a serious challenger -- someone the likes of a Christie Vilsack, who knows Iowa politics as well as anyone in the state. And to reiterate a point I made above, considering that Grassley hasn't faced a real challenge in 30 years, it's not abundantly clear that he still has what it takes to win a real race.