How conservative is Bush? How liberal is Kerry?

Northwestern University political scientists Jeffrey A. Jenkins has an interesting essay in today’s Chicago Tribune on where George W. Bush and John Kerry stand in the political spectrum, using standard methods in the study of American political science:

Looking at how the president might have voted on key ideological issues before Congress, I compared Bush’s score to those of Republican senators and other Republican presidents across time. I also looked at how Sen. John Kerry’s positions compare with other Democratic presidents, using the same kind of measures…. As it turns out, Bush is positioned near the dividing line between the center-right and right quartiles of the party. So, while clearly right of center, he is not part of the most conservative segment of the party, anchored historically by the likes of Sens. Phil Gramm and Jesse Helms. He is considerably more conservative than Dwight Eisenhower and Gerald Ford, somewhat more conservative than Richard Nixon, slightly more conservative than his father, George H.W. Bush, but less conservative than Reagan…. What about Kerry, the would-be president? Should he become president, what should we expect? How does this left-leaning moderate compare to other recent Democratic presidents? In fact, only Lyndon Johnson appears more conservative than Kerry; Jimmy Carter and Bill Clinton appear slightly more liberal; and John F. Kennedy, to whom Kerry is often compared, appears considerably more liberal than the Massachusetts senator trying to follow in his footsteps…. In the end, what does all of this mean? Put simply, the American people have a real choice in 2004. Rather than appear as “echoes,” Bush and Kerry represent very different ideological views of the world. While neither carries a distinctly extremist mentality, their views of the role government plays in the economy and society meaningfully diverge.

For an introduction to the methodology Jenkins used for this op-ed, click here. UPDATE: James Joyner provides a cogent critique of the Poole-Rosenthal method for determining ideological position:

The problem I have with Poole’s coding methodology is that it’s excessively time bound. To compare Bush 43 to Reagan or Kerry to Carter ignores massive shifts in public opinion during those time periods. The “center” is not a spot on a map; it’s a median of current attitudes.

ANOTHER UPDATE: Chris Lawrence has further thoughts on methodology. And Jenkins responds by posting comments here, here, and here. One point is particularly interesting — Poole and Rosenthal used the early 1990’s Kerry as an example of their methodology in their 1997 book Congress: A Political Economic History of Roll Call Voting. Kerry came out as quite liberal. What happened?:

What’s interesting is that over time Kerry has remained remarkably consistent, BUT the party has continued to move left. So, because of leftward movement of carry-over members along with liberal replacement of moderates, Kerry now looks left-of-center, but not extremist.