Who are the two most disagreeable United States senators?

Not disagreeable in personality, but willing to buck their own party. That would be Susan Collins of Maine and Lisa Murkowski of Alaska, both Republicans.

The pair are the most reliable Democratic supporters on roll-call votes in the current Congress. In large part because of an increase in votes on presidential nominations after Harry Reid, the Senate majority leader, limited the use of the filibuster last year, both senators are headed toward record levels of disagreement with their party.

Ms. Collins has sided with Democrats on cloture votes that allow a nomination to proceed for a vote on confirmation 82 times in this Congress.