Congressional Quarterly has analyzed the roll call voting patterns of members of Congress since 1953. The three principal studies involve:

• The frequency with which lawmakers vote with the president when he clearly indicates his preferences (Presidential Support).
• The frequency with which they vote with their party, on occasions when a majority of Republicans oppose a majority of Democrats (Party Unity).
• And the frequency with which they show up and cast "yea" or "nay" votes (Voting Participation).

This searchable and sortable table shows Party Unity, Presidential Support and Voting Participation scores for individual lawmakers who are currently serving in the 111th Congress. Scores are based on 270 roll-call votes cast in the Senate through August 6, and 684 roll-call votes cast in the House through July 31 (the House also conducted two recorded quorum calls so far this year).

As is traditional, House Speaker Nancy Pelosi, D-Calif., has not participated in most roll-call votes so far this year, so her scores may not fairly represent her positions.

More Interactive Analysis: