The announcement by Democratic Sen. Herb Kohl that he won't seek a fifth term has set the Democrats further back in their hopes of keeping the Senate during next year's elections. Kohl is the fifth Democrat to retire after next year, or sixth if you count independent Connecticut Sen. Joe Lieberman, who caucuses with the Democrats. With Democrats defending 23 seats, and a short list of Democratic incumbents running in conservative and swing states, Republicans are seeing more and more opportunities to pick up some seats. Here are the nine most vulnerable Democratic seats, in alphabetical order.
Freshmen Sen. Claire McCaskill's re-election chances took a hit after she admitted to failing to pay taxes on a private plane, which undercut her image as a moderate opponent of corruption in the Senate. The Show Me State has long been a moderate bellwether of the nation, but it has tilted to the right in recent years, voting for John McCain in 2008 and electing Republican Roy Blunt in 2010.
One of the many new Democratic faces who swept into the Senate in moderate and conservative states during the blue wave of 2006, Democratic Sen. Jon Tester will face re-election in a very different environment. He'll likely face Republican Rep. Denny Rehberg, Montana's only at-large congressman, who's held his seat since 2000.
Democratic Sen. Ben Nelson, who was first elected to the Senate in 2000, faces a tough re-election battle in Nebraska. Although Nelson has a reputation as one of the Senate's moderate deal-makers, his vote for the healthcare reform law--remember the "Cornhusker Kickback?"--may hurt him in this red state.
Democratic Sen. Jeff Bingaman's decision not to run for a sixth term in this southwestern swing state has given the GOP one of its prime opportunities to win another seat. Former five-term representative Heather Wilson has announced a bid for the seat, with the backing of former Sen. Pete Domenici, but she may face a challenge from Republican Rep. Steve Pearce, who unseated her in 2008.
The retirement of Sen. Kent Conrad, the Senate Budget Committee chairman, will likely end an era. Most political analysts believe that Democrats have virtually no chance of keeping the seat that Democrats have held for decades. Just a year ago, both seats in this deep red state were held by Democrats, but short of a disaster for the GOP, Republicans will hold both seats in 2013.
Unlike fellow endangered freshmen such as McCaskill or Tester, Democratic Sen. Sherrod Brown isn't a moderate, but a firebrand liberal in a midwestern swing state that has recently lurched to the right. On paper, he looks like a prime target, but his brand of populist liberalism has played well in this Rust Belt state, and some political observers believe Brown has the edge going into 2012. Still, Republicans look at it as a prime opportunity to pick up a seat.
Sen. Jim Webb's decision to retire from the Senate after one term paved the way for former Sen. George Allen to try to reclaim the seat, which he lost to Webb by a hair in 2006. Allen will likely face another Virginia heavyweight, former Gov. Tim Kaine, in one of the most competitive races in the country.
In 2010, then-Gov. Joe Manchin won the seat previously held by state legend Robert Byrd by running to President Obama's right, and blasting his initiatives such as a cap-and-trade bill. After winning the special election following Byrd's death, he'll have to run again for a full term in 2012, and the state GOP will have more time to prepare and make their case against him.
Kohl's retirement turns the Wisconsin Senate race into perhaps one of the most interesting in the country. Speculation has swirled that House Budget Chairman Paul Ryan may throw his hat into the ring for the Republican side. Liberals are also hoping that recently defeated Sen. Russ Feingold may try another run. The state has been at the center of the political radar lately, after the Democrats' high-profile battle with Republican Gov. Scott Walker over the collective bargaining rights of state employees. [Check out photos of the Wisconsin protests.]