FTN 2018 Midterm Election Guide: Preliminary Data

Sloan Kettering takes a look at the data and trends heading into the 2018 midterm elections.

FTN 2018 Midterm Election Guide: Preliminary Data

This is the first article in a series examining the upcoming 2018 midterm elections, and offering a comprehensive analysis of all the variables at play. This first installment will provide an overview of some general data, focusing on the math of the electoral map, voter turnout, and fundraising, among others.

Stay tuned for future installments, which will dive into a variety of topics relevant to the 2018 midterm elections, including the specifics of House races, Senate races, and Governorship races.

On Tuesday, November 6th, remember to get out and VOTE!


All 435 U.S. House seats and 33 U.S. Senate seats are up for regular elections in the 2018 midterms. Heading into the election, the Republican Party holds a majority in both chambers. Republicans currently hold a 51-49 majority in the Senate and a 235-193 majority in the House.


(Pew, 2018)

Though the electoral map favors Republicans in the Senate, the GOP is at a disadvantage in the House, with most forecasts predicating Democrats gaining control of the lower chamber. The electoral map offers key insight into how the 2018 midterm elections will play out.

The Electoral Map

Despite disadvantages in the fight to maintain control of the House, Republicans do have a few geographic advantages which suggest long term success for the GOP in the future.

For example, analysis by Gallup shows that the country is gradually growing more conservative (see figure below). Back in 2008, far more states were classified as solid blue or leaning blue, giving Democrats a 30 state advantage over Republicans. However, the 2016 data revealed that the pendulum has swung back the other way, with more states classified as solidly red or leaning red, giving the GOP a seven state advantage.

This point is corroborated by FiveThirtyEight’s David Wasserman, who wrote earlier this year that the electoral map is largely favorable to Republicans. Wasserman writes:

“Even if Democrats were to win every single 2018 House and Senate race for seats representing places that Hillary Clinton won or that Trump won by less than 3 percentage points — a pretty good midterm by historical standards — they could still fall short of the House majority and lose five Senate seats.”


Wasserman’s article also provides two graphics which illustrate the GOP’s advantages on the map. One is a graph plotting out the median seat margin relative to the nation over the last century. The other visual is a comparison of 1980’s blue electoral map with 2016’s vastly red map.

As previously mentioned, the Senate map favors Republicans. There are ten states with a Democratic incumbent that Trump won in 2016: Montana, North Dakota, Missouri, Wisconsin, Florida, West Virginia, Ohio, Indiana, Michigan, and Pennsylvania. Meanwhile, Nevada is the only state with a Republican incumbent that was won by Crooked Hillary. Additionally, while there are no states with a Republican incumbent and a Democratic governor, there are 13 states with a Democratic incumbent that have a Republican governor: New Mexico, North Dakota, Missouri, Wisconsin, Florida, Ohio, Indiana, Michigan, Maryland, West Virginia, Massachusetts, Vermont, and Maine.

Things are less cut-and-dry with the House map. There are 23 seats held by a Republican incumbent in which the district previously voted for Crooked Hillary: AZ-02, CA-10, CA-21, CA-25, CA-39, CA-45, CA-48, CA-49, CO-06, FL-26, FL-27, IL-06, KS-03, MN-03, NJ-07, NY-24, PA-06, PA-07, TX-07, TX-23, TX-32, VA-10, and WA-08. On the other hand, there are 12 Democratic districts which Trump won: AZ-01, IA-02, IL-17, MN-01, MN-07, MN-08, NH-01, NJ-05, NV-03, NY-18, PA-17, and WI-03.

Despite these structural advantages, Democrats will still have to put up a tremendous fight in order to take back control of the House in 2018.

The “Enthusiasm Gap” and Voter Turnout

You may know that midterms historically favor the party which doesn’t hold the presidency, but another trend in midterm elections is a slight Republican advantage due to lower voter turnout (many midterm voters are old, White people).


Typically, voter turnout is low in elections in which the presidency is not on the ballot. However, the data suggests 2018 could see a higher turnout than previous midterm elections, with voters from both parties indicating enthusiasm to head to the polls this November.

(NPR/PBS NewsHour/Marist, 2018)

Pollsters and pundits alike have been warning all summer of an ominous “enthusiasm gap” which will cripple Republican chances at victory in the midterms. This so-called “enthusiasm gap” refers to a gap in levels of enthusiasm to vote between Democrat and Republican voters. It is true that the data suggests this gap does indeed exist, but polling errors could mean its relevance is drastically overstated.

Amid the intense Senate Judiciary Committee hearings over the confirmation of President Trump’s latest Supreme Court nominee, Brett Kavanaugh, it appears that the controversy may have given Republicans an advantage in voter enthusiasm. Previously, pollsters had noted a significant gap in voter enthusiasm between Republicans and Democrats, but the Washington Post reports, “Since July, the percentage of Republicans saying the election is very important has increased by 12 points.”



In regards to overall voter turnout, Republicans historically have an advantage, as I mentioned before. The graph above illustrates how Democratic districts tend to have lower turnout than Republican districts, which is good news for the GOP’s chances in House races.

Generic Congressional Ballots

Pollsters use a generic ballot to determine which party is winning the race for Congress. A generic ballot simply asks the question: Will you vote for a Republican or Democrat for Congress?

So far, most polls show the Democrats winning the generic ballot. However, as Jazzhands himself has pointed out before on Fash The Nation, those numbers continue to level out, narrowing the gap—just like they did in 2016.

For reference, I’ve included the generic ballot aggregations from three major polling sites:


My survey of the available data shows advantages for both Democrats and Republicans. The GOP essentially has the Senate locked down, but the race for control of the House is still very much in play.

Stay tuned for the next installment in this guide to the midterms.

On Tuesday, November 6th, remember to get out and VOTE!

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