Roy Blunt is proving to be a pretty unpopular Senator. Only 33% of voters approve of the job he's doing to 42% who disapprove. Independents split against him 28/44 and only 54% of Republicans are happy with him compared to 63% of Democrats who give him poor marks. The fact that Blunt won such an overwhelming victory last year even though he's so unpopular is really symbolic of how brutal the climate was for Democrats in 2o1o- the GOP could have put up most anyone and won the Senate race in Missouri last year. Blunt's someone who could be really vulnerable if he was running in a year that was good for Democrats or even pretty neutral. But his timing was perfect last year.
As the Star's Dave Helling notes, PPP's work the last cycle "actually exhibited a slight bias toward Republican candidates," despite their progressive orientation and client list.