I wish no ill will towards her, but her liberal bonafides are severely overstated. From the Wiki:
Since being elected to the Senate, McCaskill has consistently been named by the National Journal in its ideological rankings as one of the ten most moderate Senators.[23] In 2011, she was ranked exactly 50th on its scale of most-liberal to most-conservative.[24] The Washington Post reported in 2012 that she was the second-most-likely Democratic Senator to vote against her party.[23]
Since being elected to the Senate, McCaskill has consistently been named by the National Journal in its ideological rankings as one of the ten most moderate Senators.[23] In 2011, she was ranked exactly 50th on its scale of most-liberal to most-conservative.[24] The Washington Post reported in 2012 that she was the second-most-likely Democratic Senator to vote against her party.[23]