The Sunlight Foundation sponsors a searchable database called OpenCongress, and among other nifty features, you can track voting trends for individual Senators. Which makes it child’s play to figure out which other Senators your target Senator most often votes with, and vice versa.
And speaking of Larry Craig, OpenCongress shows that he most often votes with a guy named Mike Crapo (R, Idaho). Only makes sense, given that they both represent Idaho, and look to present a unified front.
But who is Craig least likely to vote with? That would be Bernard Sanders (I, Vermont).
To recap, then:
Larry Craig most often with Crapo.
Pretty much never with Bernie.
Just so we’re all clear on that.