Decision 2018 – JMC Analytics and Polling’s 10/11 US House scorecard – The Road To 218

Six days ago, JMC assessed the partisan climate of 435 US House races using a combination of election and polling data. In making these assessments, JMC noted the electoral reality that the “split ticket” voter (i.e, a voter who supports candidates from different parties for Presidential and “downballot” races such as Congressional races) has been in decline ever since the early 1990s, and with voters’ being increasingly likely to vote the same way (i.e., a “straight ticket” voter) both in Presidential and Congressional races, the 2016 Presidential vote for all 435 U.S. House districts is a good place to start for (theoretically) assessing how “solid” a House district is for either party. The following criteria are used:

Defining JMC’s “watch list”:

Most vulnerable: a House Republican represents a district that gave President Trump less than 50% of the vote in 2016 (or a Democrat representing a district President Trump carried with an absolute majority). 41 districts meet this criteria (37 represented by Republicans, 4 by Democrats). These districts narrowly supported Hillary Clinton 47-46% (about the national popular vote), and in a partisan wave, these districts are likely the first ones to flip;

Moderately vulnerable: a House Republican represents a district that voted between 50-55% for President Trump in 2016 (or a Democrat representing a district President Trump carried with a plurality of the vote). An additional 60 districts meet this criteria (52 represented by Republicans, 8 by Democrats). These districts overall supported Trump 52-43% over Hillary Clinton, so these districts hypothetically (without taking into consideration candidate strengths/weaknesses) have “Republican votes to spare”, and would therefore be less likely to flip in the “straight ticket” environment of today, unless the partisan wave were substantial;

Minimally vulnerable: a House Republican represents a district that voted between 55-60% for President Trump in 2016 – except under extraordinary circumstances, the assumption here is that even if the Republican candidate is weak, there are more than enough “Republicans to spare.” 52 districts (all Republican held) meet this criteria, and these districts supported Trump 57-38% over Hillary Clinton;

Given the detailed criteria above, JMC is watching 153 House districts (141 held by Republicans, 12 by Democrats) – the assumption for the remaining 282 House districts is that the Trump (or Clinton) percentage is high enough for it to be extremely unlikely for any of these seats to flip.

Applying JMC’s “watch list” to actual (election and polling) data:

Given that the Presidential percentage is more theoretical in nature, what does actual polling data (or in the case of nonpartisan primaries in California and Washington State, primary election data) say? (Caveat: polling/election data is only available for 68 of the 153 House seats placed on the “watch list”)

Most vulnerable seats (33 have poll and/or primary election data)

  • 5 safe Republican seats (was 4 last week);
  • 13 Republicans and one Democratic seat are too close to call  – “too close to call” meaning the leading candidate is ahead by less than 5 points (was 11 Republican and 1 Democrat last week);
  • 14 Republicans are trailing by 5 or more points, and therefore, these seats are likely to “flip” (was 12 Republicans last week);

Moderately vulnerable seats (24 have poll and/or primary election data)

  • 11 seats are safe Republican (was 9 last week);
  • 1 seat is safe Democratic (no change);
  • 9 Republican seats are too close to call (was 7 last week);
  • 3 Republicans are trailing by 5 or more points (was 2 last week);

Minimally vulnerable seats (11 have poll and/or primary election data):

  • 7 are safe Republican (was 5 last week);
  • 4 Republican seats are too close to call (no change since last week). 

To summarize, this sample of 68 House races (out of a population of 153 House districts) where polling and/or election data is available shows the following:

  • 23 safe Republican and 1 safe Democratic seats (was 18 Rep, 1 Dem last week);
  • 26 Republican and 1 Democratic held seats are “too close to call” (was 23 Rep, 1 Dem last week);
  • 17 Republicans trail by 5 or more points (was 14 Rep last week).

October 11 House scorecard






If this sample of 68 were extrapolated to the entire population of 153 seats on JMC’s “watch list”, that would suggest a Republican loss of 23 seats (21 last week), with 54 Republican (and 4 Democratic) seats too close to call (was 60 Republican, 4 Democrats last week).

What is the political complexion of those 27 seats that are “too close to call” ? These seats on average voted 49-44% for President Trump while at the same time supporting the Republican incumbent in 2016 with 57% (in other words, Congressional Republicans ran 8 points ahead of President Trump in 2016). The fact that these seats are 7 points more “Republican friendly” than the national average and tossups is indicative of the Republicans problems in the House.

For the 17 seats where Republicans are trailing, Clinton carried these districts 49-45% – a bit more Democratic than the national average. These same seats also voted 54% Republican in 2016 Congressional races (in other words, Republican candidates ran 9 points ahead of President Trump). Given that President Trump’s approval ratings have remained in the low to mid 40s (just under his popular vote share), that is why these 17 Republicans are in trouble, since polling shows they haven’t run sufficiently ahead of the President.

Has the controversy over the Kavanaugh nomination made a difference, like it seems to have in several Senate races? Unlike the Senate races (which are held more on Republican turf), Kavanaugh’s energizing the Republican base is less likely to matter on the House side because of the terrain where House/Senate races are being fought. The competitive Senate contests (Arizona, Florida, Indiana, Missouri, Montana, Nevada, North Dakota, Tennessee, Texas, and West Virginia) are being fought in territory that supported Trump 53-43%, The House races where 89 Republicans are most or moderately vulnerable supported Trump by a narrower 49-45%.

As additional House race polls are released, this analysis will be revisited; the point of this analysis was to show (using available Presidential, primary, and polling data) why Republicans face the very real possibility of losing their House majority for the first time since 2006.