FILE - In this Sept. 21, 2011 file photo, Sen. Claire McCaskill, D-Mo. listens on Capitol Hill in Washington. Democrats have their thumbs heavily on Republican scales in Senate primaries in Missouri ... more 
FILE - In this Sept. 21, 2011 file photo, Sen. Claire McCaskill, D-Mo. listens on Capitol Hill in Washington. Democrats have their thumbs heavily on Republican scales in Senate primaries in Missouri and Wisconsin this summer, hoping to tip the balance and improve their own chances of maintaining a majority in November. The idea isn't as far-fetched as it might sound. (AP Photo Manuel Balce Ceneta, File) less 
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Associated Press
Sun, Jul 29, 2012 8:32 AM EDT