Politics: Liberal & Conservative Leanings Over Time

A system called DW-Nominate, developed by a group of six political scientists, rates each member of Congress on a scale from negative 1 (very liberal on economic issues) to positive 1 (very conservative) based on their roll-call votes. The system also creates a score for each president based on cases in which the outcome he desired from a vote in Congress was clearly articulated.

Whereas Democratic presidents usually have scores fairly close (but just slightly to the left of) the median Democratic member of Congress, Republican presidents — with the very clear exception of Eisenhower — articulate legislative positions that are equivalent to those held by one of the most conservative members of their party.

We need to be careful in interpreting these results. The positions that presidents advocate on Congressional roll calls can be subject to a number of tactical considerations, and may not be entirely representative of their ideology.

For more, see How Liberal Is President Obama? by Nate Silver, April 29, 2011 at FiveThirtyEight at the New York Times.