The cutting line (separating predicted Yea votes from predicted Nay votes) divides the 75 Yea Republicans from the 167 Nay Republicans along both the first dimension (representing liberal-conservative position) and the second dimension. The meaning of the second dimension has largely shifted from representing regional differences within the parties (e.g., between northern and southern Democrats) to intra-party divisions that are more subtle and less clear. One of these divisions appears to be an “insider vs. outsider” cleavage that pops up on votes such as raising the debt ceiling, domestic surveillance, and government funding bills.
This image is from a new stand-alone DW-NOMINATE that can be run daily as new roll calls are cast. We will have more to say about this software at a later date.
Click image to enlarge
Note: The plot shows only 256 Yea votes because Speaker John Boehner (R-OH) voted Yea but has not cast enough votes (25) to be included in the scaling.