The website GovTrack is a useful source for tracking legislation and various members of Congress. From the data available on the type of legislation members of congress co-sponsor, and how they vote on legislation, they’re able to create a score to rank where they stand ideaologically. According to GovTrack their scores for members of Congress are based on their legislative behavior, and by “how similar the pattern of bills and resolutions they cosponsor are to other Members of Congress.”
Scores rank from 1.00 (most conservative) to 0.00 (most liberal).
An obvious disclaimer is that all estimates of relative political ideology are just that – estimates.
These scores don’t take into account public statements that politicians make. So if Bernie Sanders called for nationalizing railroads on MSNBC but didn’t vote for or sponsor any legislation related to that, it wouldn’t show up in this sort of score of ideology. Another disclaimer is that this data is only for a single year, not based on the cumulative voting records of Congressmen.
GovTrack founder and President Joshua Tauberer acknowledges that his estimates, just like any estimates, are imperfect: “We always say that one number can never represent the complete picture of a politician.”
That aside, their score does provide one estimate of who the most and least conservative members of Congress are. Their most recent estimates are from 2019, the last full calendar year.
In the Senate, the ten most conservative members are:
- 1.00 Sen. Marsha Blackburn [R-TN]
- 0.96 Sen. Joni Ernst [R-IA]
- 0.91 Sen. Mike Braun [R-IN]
- 0.91 Sen. Ted Cruz [R-TX]
- 0.91 Sen. James “Jim” Inhofe [R-OK]
- 0.91 Sen. Kevin Cramer [R-ND]
- 0.90 Sen. Tom Cotton [R-AR]
- 0.90 Sen. John Cornyn [R-TX]
- 0.89 Sen. James Risch [R-ID]
- 0.88 Sen. Marco Rubio [R-FL]
Admittedly I was surprised to see Rubio make the top ten. The ten least conservative (i.e. most liberal) Senators are:
- 0.00 Sen. Kamala Harris [D-CA]
- 0.02 Sen. Bernard “Bernie” Sanders [I-VT]
- 0.03 Sen. Kirsten Gillibrand [D-NY]
- 0.07 Sen. Jeff Merkley [D-OR]
- 0.07 Sen. Cory Booker [D-NJ]
- 0.09 Sen. Mazie Hirono [D-HI]
- 0.10 Sen. Edward “Ed” Markey [D-MA]
- 0.12 Sen. Richard Blumenthal [D-CT]
- 0.14 Sen. Amy Klobuchar [D-MN]
- 0.15 Sen. Richard Durbin [D-IL]
- 0.16 Sen. Chris Van Hollen [D-MD]
Interestingly, there are a handful of Senate Democrats who are more conservative than some Republicans. While there are 53 Republicans in the Senate, the 47th most conservative Senator is Arizona Democrat Kyrsten Sinema, the 50th most conservative is Alabama Democrat Doug Jones, and the 53rd is West Virginia Democrat Joe Manchin. Both Susan Collins and Lisa Murkowski (ranked 54th and 56th respectively) are less conservative than those three. Murkowski is the least conservative Republican Senator, while Kamala Harris was to the immediate left of a socialist last year.
In the House of Representatives the ten most conservative Reps are:
- 1.00 Rep. Mark Meadows [R-NC11, 2013-2020]
- 0.96 Rep. Ralph Norman [R-SC5]
- 0.90 Rep. Ron Wright [R-TX6]
- 0.90 Rep. Matt Gaetz [R-FL1]
- 0.89 Rep. Vicky Hartzler [R-MO4]
- 0.89 Rep. Alex Mooney [R-WV2]
- 0.89 Rep. Paul Gosar [R-AZ4]
- 0.88 Rep. Ted Budd [R-NC13]
- 0.88 Rep. Debbie Lesko [R-AZ8]
- 0.88 Rep. Randy Weber [R-TX14]
And the ten least conservative (i.e. most liberal) Representatives are:
- 0.00 Rep. Barbara Lee [D-CA13]
- 0.03 Rep. Janice “Jan” Schakowsky [D-IL9]
- 0.03 Rep. Eleanor Norton [D-DC0]
- 0.06 Rep. Bonnie Watson Coleman [D-NJ12]
- 0.06 Rep. Ayanna Pressley [D-MA7]
- 0.06 Rep. Sheila Jackson Lee [D-TX18]
- 0.07 Rep. Raúl Grijalva [D-AZ3]
- 0.07 Rep. Adriano Espaillat [D-NY13]
- 0.07 Rep. Ilhan Omar [D-MN5]
- 0.07 Rep. Debra Haaland [D-NM1]
Socialist Alexandria Ocasio was the 17th most liberal.
The most conservative Democrats are Minnesota’s Collin Peterson, with an ideology score of 0.62, and New Jersey’s Josh Gottheimer with an ideaology score of 0.62. They’re the 144th and 147th most conservative members of the House (where Republicans hold 197 seats). Kevin McCarthy ranked #219th, making him the least conservative Republican with an ideology score of 0.42. In 2018 Paul Ryan was the least conservative Republican.
That’s just 2019 – it’ll be interesting to see how they change when the data for 2020 is in.