On one side, there's Republican Tommy Thompson, the former Governor and Bush administration official who is perceived as too moderate for some in his own party.Thompson barely survived a bruising primary fight against Republicans.
Republicans have been energized, however, not only by the successful defense of Governor Scott Walker in the recall election but also by the chance to have two Republican Wisconsin U.S. Senators, which hasn't happened since the 1950's.
On the other side is Rep. Tammy Baldwin, a liberal Democrat from the Madisonarea.Baldwinis also openly gay in a state which has areas that are typically morally conservative.
The seven-time incumbent Congresswoman has been able to take advantage of Thompson's vulnerability after his tough primary fight. Baldwin outspent Thompson and successfully courted outside groups seeking to defend the Democratic majority in the U.S. Senate.