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What’s gonna happen in the 2018 midterm elections?

Following up on yesterday’s post on party balancing, here’s a new article from Joe Bafumi, Bob Erikson, and Chris Wlezien giving their predictions for November:

We forecast party control of the US House of Representatives after the 2018 midterm election. First, we model the expected national vote relying on available generic Congressional polls and the party of the president. Second, we model the district vote based primarily on results from 2016 and the national swing. . . . Based on our analysis, the Democrats are projected to win a solid plurality of the national vote, above 53% of the two-party share, and gain control of the House with a narrow 7-seat majority. Our simulations yield considerable variation, however, with the Republicans winning the majority of seats 46% of the time but with the distinct possibility of a big Democratic wave.

No scatterplot, unfortunately. Also, whassup with the weird y-axis labels above, huh? Anyway, if you stare at the graph long enough, the point is clear: The system is asymmetric, what we call a Republican bias in the seats-votes curve. Democrats need quite a bit more than half the votes to be assured of half the seats in the legislature.

Erikson adds:

Past wave elections have been surprisingly strong. One reason is that seats that had previously seemed safe for incumbents suddenly became endangered. Why? In the prior election, the out-party (Dems today) had not competed strongly for a seat that they could only come close to winning but not win. The combination of a wave of new support for the out party plus the out party’s renewed effort can tip the balance where incumbents had previously seemed safe enough.

With a super-sized wave (bigger than observers now predict), the fallout can be enormous because gerrymandering only rearranges district lines and cannot manufacture more votes for a party. So designers of gerrymanders ignore the possibility of a 100 year flood—so their dikes are shallow. A large wave can wash away many in-party seats. I hope this analogy is clear.

But as of now the generic polls do not show a super-sized wave. The central question is more modest: which party controls the House. The Democrats are favored but not certain of winning the most seats.

Meanwhile, if there is the wave that people think is coming, the Senate might be more in play than people think today. A strong blue wave could probably help almost all if not all of the vulnerable Democrat Senators survive. Meanwhile the Dems could pick up 1 to 4 seats, possibly regaining a Senate majority.

6 Comments

  1. Secaucus says:

    # “The Democrats are favored but not certain of winning the most seats. “

    Maybe yes, maybe no … but we can not possibly wait 3 months to know the official election results. These soft political prognostications are so very very important to Americans — because why ??

    What makes Bafumi/Erikson/Wlezien guesses especially worth reading among all elections seers?

    • Andrew says:

      Secaucus:

      It is not a matter of waiting 3 months “to know the official election results.” The election hasn’t happened yet; “soft prognostication” is all we can get. Bafumi et al. are not “seers”; they are analysts. Finally, why do many Americans care about which party will win control of congress? For the same reason many non-Americans care: because politicians make decisions that affect millions of people, including issues such as health care funding, abortion, trade, foreign policy, etc.

  2. gregor says:

    Democrats do seem to get relatively few house seats relative to total votes, and this is always attributed to gerrymandering. But I think they have a more fundamental, mathematic disadvantage. When your votes are concentrated in cities and you have precincts where you win 99% of the vote, it will be very difficult to avoid “wasted votes.” To “correct” this you’d have to take urban votes and somehow spread them out among remote areas, exactly the sort of geographic contortions that “gerrymandering” traditionally refers to. Moreover, it would likely run afoul of the Voting Rights Act which is designed to preserve black-majority districts and prevent dilution of black votes. Repealing those protections probably would help the Democrats get more seats overall but at the expense of black legislators.

    • Anonymous says:

      These types of “strategies” sound ridiculous to me. Why don’t democrats instead try to have a platform that appeals to a wider demographic, ie the will of the people? I mean isn’t this year shaping up to be the “spook wave”?

      One quarter of all the Democratic challengers in competitive House districts have military-intelligence, State Department or NSC backgrounds. This is by far the largest subcategory of Democratic candidates. National security operatives (57) outnumber state and local government officials (45), lawyers (35), corporate executives, businessmen and wealthy individuals (30) and other professionals (19) among the candidates for Democratic congressional nominations.

      Of the 102 primary elections to choose the Democratic nominees in these competitive districts, 44 involve candidates with a military-intelligence or State Department background, with 11 districts having two such candidates, and one district having three.

      https://www.wsws.org/en/articles/2018/03/07/dems-m07.html

      • Terry says:

        One quarter of all the Democratic challengers in competitive House districts have military-intelligence, State Department or NSC backgrounds. This is by far the largest subcategory of Democratic candidates. National security operatives (57) outnumber state and local government officials (45), lawyers (35), corporate executives, businessmen and wealthy individuals (30) and other professionals (19) among the candidates for Democratic congressional nominations.

        Sounds like you’ve got the makings of a pretty good conspiracy theory there.

    • ScottA says:

      I think this is pretty much undeniably true. The other side of gerrymandering that people always forget is that incumbents in gerrymandered districts don’t want them to change. They like getting 90% of the vote. An optimal distribution for a party always means more risk to individual legislators; you have to take some of their votes and give them to other candidates.

      And, a random thing on the overall post – I don’t love nationalized models applied to house elections. Every truly swing district is pretty context-driven (scandals, corruption, weird partisans that differ from the national party on key issues, etc.) Although I grant I haven’t run a fully analysis of correlations between this kind of national vote measure and vote changes in swing districts, so maybe it works great.

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