04/23/2012 12:34 am ET

Claire McCaskill Fights Super PAC Influence As Senate Seat Comes Under Siege

As one of the U.S. Senate’s most endangered Democratic incumbents, Claire McCaskill knows she’s a top target of the new conservative super PACs that have radically reordered the political landscape in 2012.

Independent conservative groups have already spent more than $3 million on television and radio ads in Missouri hoping to pick up one of the four seats that Republicans need to take control of the Senate.

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