Political Scientists Say Obama Might Be More Liberal Than Hillary

As James and Alex discuss below, the National Journal just released its 2007 rankings of Senators and found that Barack Obama had the most liberal voting record based on 107 “key votes” in the Senate in 2007. As legislative politics scholar Sarah Binder notes, this does not comport with Poole and Rosenthal’s NOMINATE scores, nor does it correspond with Lewis and Poole’s more recent Optimal Classification technique (via Kieran Healy), both of which show Obama to be much closer to the median Democrat.

Just to throw more fuel on the fire, I ran Clinton, Jackman, and Rivers’ item-response-theory-based ideal point estimator (sorry, it doesn’t have a fancier name–we in the biz just call it “CJR”) on all 433 non-unanimous rollcalls for the 110th Congress. The results suggest that Obama has the 9th most liberal voting record in the Senate, with rival Hillary Clinton in 11th place and very little daylight between them. Statistically, we can say that there is a (very slim) chance that either Obama or Clinton is the most liberal senator, as the 95% credible boundaries for both senators’ voting records overlap those of New Jersey’s Robert Menendez, who is nominally the “most liberal” according to the means. Both, incidentally, are slightly more liberal than John Kerry according to the procedure.

110th Senate legislator ideal points
The most liberal senators (click for the full 110th Senate).

On the Republican side, John McCain appears in the middle of the GOP pack, as the 20th most-conservative senator, with no credible chance of being the “most conservative” (a rating that South Carolina’s Jim DeMint runs away with). McCain is, however, more conservative than GOP stalwarts like Orrin Hatch, Thad Cochran, Sam Brownback, and Lamar Alexander.

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Chris Lawrence
About Chris Lawrence
Chris teaches political science at Middle Georgia State University in Macon, Georgia. He has a Ph.D. in political science (with concentrations in American politics and political methodology) from the University of Mississippi. He began writing for OTB in June 2006. Follow him on Twitter @lordsutch.


  1. yetanotherjohn says:

    However you package it, both Obama and Clinton are from the far left wing of US politics (and those viewing from the left may see a huge difference, but they are both far to the left of the median US voter).

    However it looks like from the right, McCain is well to the right (but a lot closer than Obama or Clinton) of the median US voter.

    Obama is not well known for the average voter, but he will get labeled as liberal and the label will stick because it is true (see his voting record). There is nothing per se wrong with being liberal, but it is a political position that is at odds with the median US voter.

    But the real fun is going to happen when we get a viable third party contestant (viable not in winning, but viable in the sense of taking enough votes in enough states to flip the EV results).

  2. McGehee says:

    more conservative than GOP stalwarts like Orrin Hatch … and Lamar Alexander.

    I hope McCain didn’t injure himself outdoing those guys.

  3. Scott says:

    What are your standards for “liberal” and “conservative”? With issues like strong usfg, the drug war, and support for israel being basically undiscussed among factions, I’m interested to see what the definition has grown into.

  4. Scott says:

    Rethinking my comment, I think the bigger danger is actually breaking votes down into a single spectrum, especially with the up-and-coming Ron Paul-itic where libertarians are being bred among social liberals and Liberal Economists (lassiez-faire). My godshonest opinion is that single-spectrum breakdowns are preventing us from getting the real picture behind the political landscape of a slowly-emerging three-party state.