The big unanswered question of the 2010 elections is: will the Republicans recapture the House, the Senate, or both ? Currently, the House is controlled by the Democrats 256-179, while the Senate is controlled by the Democrats by a 59-41 margin. Since most of the information about this subject on either side of the political spectrum is colored with a considerable amount of spin, we’ve decided to perform the analysis ourselves using a combination of theory and “real world” data to quantify those gains. In this article, we’re focusing on the House of Representatives.

The “Obama Plunge” in theory

The genesis of our analysis came from several sources. The first source was actual election results. Though we’ve always believed that the 2008 Presidential election results were a “high water mark” for popular support of the Democratic party’s agenda, we did not have any hard evidence to validate this assertion until we had the results of four elections: Governor’s races in New Jersey and Virginia, a special House election in the San Francisco Bay area of California, and a special Senate election in Massachusetts). In all four of those races, we noticed that Democratic performance in those elections was consistently 12-15% less than the vote for Barack Obama in 2008. This drop in Democratic support was consistent and noticeable enough for us to give it a name: the “Obama Plunge.”

A closer examination of the overall data, however, revealed that this “plunge” was not distributed evenly across all demographic groups. In the university towns in Massachusetts and in heavily Democratic Palm Beach, the plunge was a more modest 4-6% of the vote – hardly enough for a Republican to be competitive. We therefore concluded that if a given district had a significant “base Democratic vote” (i.e., the blacks, Jewish voters, academics, and those who depend on government funding for their livelihood), the “Obama plunge” would be negligible.

Using this criteria, which House seats did we think were vulnerable ? We started with an assumption that an  “Obama plunge” of 15% (this number is based on recent election data) meant that any Democrat in a district that voted 65% or less for Obama that did NOT have significant numbers of ”base Democratic votes”  faced the very real possibility of being swept out of office. However, only using the Presidential vote as a basis for determining who is vulnerable meant that 166 Democratic held House seats would be rated as vulnerable for takeover – hardly a reasonable conclusion.

Needless to say, this was a one dimensional analysis that ignored several intangible considerations: (1) the power of incumbency, (2) the reality that Republicans would not nominate the “perfect” challenger in all 166 House seats (and that’s assuming that Republicans even contested all of those seats), and (3) the possibility of third party candidacies causing Democrats to be re-elected with less than 50% of the vote – in fact, in 1994, 8 Democratic House incumbents and 2 Democratic Senate incumbents survived for this very reason. Therefore, to address these intangibles, we added another criteria: the 2008 re-election percentage of a Democratic incumbent, with the 15% “Obama plunge” factored into that number.

While all this historical data is a good starting point, things can change between election cycles. Therefore, we also decided to consider the voting record of an incumbent Democrat on controversial legislation initiated in the House. That legislation includes the stimulus, “cap and trade”, healthcare reform, raising the national debt ceiling, and “deeming” the Democratic budget approved (i.e., passing a budget without explicitly voting on it). In general, we believe that an incumbent in a “competitive” district was more vulnerable the more that he/she supported the Democratic agenda listed above. Furthermore, we believe that voting for healthcare even once was the one vote that mattered to voters when evaluating whether an incumbent deserved to be re-elected.

The factors mentioned thus far are all theoretical in nature. There is one more theoretical factor we believe matters in assessing how safe/vulnerable an incumbent is: his/her public conduct – there are several documented instances captured on camera of inappropriate behavior (behaving rudely to constituents, threatening innocent bystanders, and the like) that could be used effectively against an incumbent in a 30 second ad.

Now that we have a comprehensive set of criteria used to evaluate what we think will happen in an individual House race, there is one more important piece of the puzzle between now and election day: poll data that has been released for various House districts – now that 35 states have held their primaries, we are beginning to see a steady stream of polling.

The “Obama Plunge” in practice

Given the criteria mentioned above, we compiled a list of (1) all Republican held seats (whether open or not) whose districts were carried by Obama (the assumption being that a McCain district held by a Republican is safe this year), (2) all Democratic held seats (whether open or not) that voted 65% or less for Obama (and if not an open seat, the incumbent received with 65% of the vote or less in 2008). From this list of 200 House seats (166 held by Democrats, and 34 held by Republicans), we are ranking Democrats and Republicans based on the following criteria, in order of priority:

(1) Poll results in any of those 200 House districts – once a Congressman reaches 50%, we deem  him/her safe. A lead in the polls with less than 50% means he/she is on the “watch list”. An incumbent who is trailing is rated as “vulnerable.”

(2) ”Congressmen/women behaving badly” – confrontational conduct by incumbent Congressmen (especially if caught on camera) which demonstrates a “let them eat cake” mentality automatically makes a Congressman vulnerable.

(3) If a district has a significant “Democratic base vote” (minorities, academic liberals, Jewish voters, or government workers), we believe, in the absence of polling to the contrary, that the “Obama plunge” will not be significant enough for Republicans to have a chance to take the seat.

(4)   (For incumbent Democrats), his/her voting record on major legislation (the stimulus, “cap and trade”, raising the national debt ceiling, and the five healthcare votes taken). We believe that in general, voting against the Democratic agenda a majority of the time insulates an incumbent from defeat, unless the incumbent Democrat voted “Yes” at least once on healthcare reform.

At the time this article is being written, 31 Republicans and 69 Democrats are rated as “safe.” There are 19 Democrats and one Republican (Joseph Cao of New Orleans, Louisiana) who are on the “watch list.” Finally, we think that 62 incumbent Democrats and 16 open House seats are vulnerable for takeover – in other words, we currently project a 78 seat GOP gain in the House. The list of those seats is here.