Which Senate Republicans have voted the most often with the Obama Administration so far?
Yes, the Senate is actually voting on stuff. Not a lot of stuff, but there are perhaps seven nontrivial votes for us to chew over. These include confirmation votes for Tim Geithner and Hillary Clinton, the bailout extension, both a cloture vote and an up-and-down vote the Ledbetter Fair Pay Act, and both a cloture vote and an up-and-down vote on the Omnibus Public Land Management Act.
One Republican, Olympia Snowe of Maine, has taken the administration's position on all seven votes, as indicated by a blue square in chart below. Two, David Vitter of Louisiana and Jim DeMint of South Carolina, have gone 7-for-7 in opposing the administration (as denoted in red). A couple more thoughts follow after the graphic.