By Bob Katzen

The percentage next to the senator’s name represents the percentage of times the senator supported his or her party’s leadership. The number in parentheses represents the number of times the senator opposed his or her party’s leadership.

Some senators voted on all 286 roll call votes. Others missed one or more roll call. The percentage for each senator is calculated based on the number of roll calls on which he or she voted and does not count the roll calls for which he or she was absent.