Previously in this post, we assessed the vulnerability of House Democrats by using the following criteria:

(1)    Whether the district voted 65% or less for Obama – 65% was significant to us, because after analyzing (a) Governors races in New Jersey and Virginia; (b) the special election in Massachusetts that Republican Scott Brown won in an upset; (c) a special election in a heavily Democratic House district in California last November, we noted up to a 15% drop-off in Democratic support compared to Obama’s 2008 showing in those areas (we have repeatedly referred to this drop-off as the “Obama plunge”) ;

(2)   Whether an incumbent was re-elected with 65% or less of the vote in 2008: while an incumbent’s popularity isn’t necessarily tied to President Obama’s 2008 showing, we believe that the “Obama plunge” can effect re-election percentages;

(3)   An incumbent Democrat’s voting record with regards to the stimulus, “cap and trade”, healthcare reform, and raising the national debt ceiling, with the further rationale of (a) If an incumbent Democrat voted mostly “No” on these four items, we believe he/she is safe. Likewise, if an incumbent Democrat voted mostly “Yes”, we believe he/she would be vulnerable. And if he/she voted “Yes” as many times as “No”, the tiebreaker would be how the district voted for President. If McCain carried the district, the incumbent may be vulnerable, while he/she is probably safe if the district voted for Obama.

The rules of the game were rewritten again today, as the House of Representatives, in a series of three votes, endorsed the Senate version of healthcare reform despite unanimous GOP opposition and significant Democratic defections. Though the bills passed with few votes to spare (those three votes were 224-206, 219-212, and 220-211, respectively), we now believe that whether an incumbent Democrat voted once or all four times for healthcare reform (we’re including the November 2009 healthcare vote in this analysis) that Democrat has now been identified as “voting for healthcare reform.” Therefore, we now believe the following are an appropriate metric for assessing the re-election chances of an incumbent House Democrat:

(1)   We still believe that an incumbent Democrat who was re-elected with more than 65% of the vote in 2008 is safe regardless of his/her healthcare vote;

(2)   We also believe that open Democratic seats where Obama got less than 65% of the vote will flip to the GOP;

(3)   We believe the GOP will hold onto its open seats and incumbents, except for New Orleans Republican Joseph Cao, whose district voted 75% for Obama;

(4)   A Democratic incumbent who has voted  “no” most of the time on the Democratic agenda and did not vote “yes” on ANY of the four roll call votes held on healthcare will likely be safe;

(5)   A Democratic incumbent who has voted  “yes” most of the time on the Democratic agenda, or who voted  “yes” on ANY of the four healthcare votes is likely vulnerable now.;

Given these refined criteria in light of the three healthcare votes which occurred today, we foresee a net GOP gain this fall of 79 seats. Curiously, this is a decrease of 5 seats from our earlier projection. Why the decrease in the number of possible GOP pickups ? By analyzing the votes of House members, there were 8 Democrats who were vulnerable in our previous analysis because they voted with the Democratic leadership half the time, but represented districts McCain carried or gave Obama only a modest margin. We believe their re-election chances were strengthened by voting no on all three healthcare roll call votes today (these 8 Democrats all voted no on the November bill). Conversely, three Democrats who seemed safe before today voted at least once for healthcare today, and are thus more vulnerable now.