In a previous post, That’s My Congress took a look at Senate cosponsorship records of the 112th Congress. We found that Republican Senator Scott Brown was rather strongly inclined to sign on in support the legislation of Democrats (a full 61.7% of his cosponsorships), while Democratic Senator John Kerry was only mildly inclined to sign on in support of the legislation of Republicans (only 19.2% of his cosponsorships).
Does this pattern hold for roll call votes in the 112th Congress? To find the answer, we look to OpenCongress.org, which maintains a list of how often senators vote with a majority of their own party. Of the 47 Senate Republicans, Scott Brown is the third-most-likely to vote against a majority of his own party — he does so 29% of the time. On the other hand, of the 51 Senate Democrats, fellow Massachusetts Senator John Kerry is the sixth-least-likely to vote against a majority of his own party. Kerry votes with the majority of Democrats 95.8% of the time.