Below we plot the first dimension DW-NOMINATE Common Space scores of the presidents in the post-war period, which we refer to as the “presidential square wave” due to its shape. An ideological score is estimated for each president throughout the entirety of their tenure in office by scaling their “votes” on a subset of roll call on which they announce a position (measured using CQ Presidential Support Votes). Negative DW-NOMINATE scores indicate greater liberalism and positive scores indicate greater conservatism. The presidential scores are directly comparable across time and with members of Congress.

These presidential DW-NOMINATE scores are estimated using all available CQ presidential support roll calls through 2013. CQ does not issue all of its presidential support roll calls until the print version of its congressional roll call guide comes out, and so only a fraction of the 2014 votes are available.

Very little has changed from the last presidential square wave. President Obama fits the spatial model estimated by DW-NOMINATE extremely well, with over 95% of his “votes” correctly classified. Obama has moved very slightly leftward (-0.367) and is now just to the left of LBJ (-0.346) and right of Truman (-0.368), though this trio is virtually ideologically indistinguishable. President Eisenhower is the most moderate president (0.293) of the post-war era.

Among members of the 113th Congress, President Obama is very ideologically close to Representatives Stephen Lynch (D-MA) [-0.364] and Loretta Sanchez (D-CA) [-0.369] in the House, and Senators Patty Murray (D-WA) [-0.367] and Mark Udall (D-CO) [-0.359] in the Senate.

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