FILE - In this Sept. 21, 2011 file photo, Sen. Claire McCaskill, D-Mo. listens on Capitol Hill in Washington. Claire McCaskill, one of the most vulnerable Democrats up for re-election in 2012, plans to skip the Democratic National Convention in Charlotte, N.C. McCaskill's campaign said Tuesday she will spend the week campaigning in her home state instead. (AP Photo Manuel Balce Ceneta, File)