Congressional Quarterly has its analysis up of the voting records of the members of congress.
Their analysis shows that Kagen votes with Obama 88% of the time. This is not entirely surprising given the President's personal popularity.
More discouraging is his record on what CQ calls Party Unity. This is defined as voting with one's party on an item where a majority of Republicans oppose a majority of Democrats.
Kagen's Party Unity number is 99%. This may explain his recent inability to deviate from the party line when voting for cap and trade.
Kagen also scored a 97 on participation, which I give him credit for. It's clear he is in Washington to do business. Now if we could just get him to concentrate on the business of the people of Wisconsin's 8th congressional district.
Here is the vote analysis for the complete House and Senate in case you want to check Baldwin, Kind, Petri, and others.