What Republican will run against Sen. Claire McCaskill in Missouri in 2012?

Not Jim Talent.

The St. Louis Post-Dispatch's Jake Wagman reports that Talent, the former Republican senator who lost to McCaskill in the 2006 Democratic wave, will not run against her a second time:

"There's just a lot of unfinished business that is a top priority for me, and that is where my interest and my passions are. I thought I could serve my country and my family better by continuing that work," Talent said in an interview with STLtoday.

"I talked to my political advisers and asked, can I run and keep doing all these things at the same time? They said, 'No, you can't,'" he added.

Talent planned to formally announce his decision in a statement on Friday.

Republicans have their eye on Missouri in 2012, and the race will likely draw national interest from tea partiers. At least one prominent, national tea party group has interviewed candidates in Missouri and plans to get involved in the race.

Talent's decision could be taken as good news or bad. He's the biggest political name in Missouri who could challenge McCaskill, but he lost last time around.

Missouri is the consummate presidential bellwether state, and John McCain won it by a razor-thin margin in 2008. In November, Rep. Roy Blunt (R) defeated Secretary of State Robin Carnahan (D) by more than 13 percent.

Which means that Missouri could provide Republicans with a solid opportunity to gain a Senate seat in 2012.