Tag Archives: 2020 House Forecast

FORECASTING THE HOUSE: PROJECTIONS BASED ON THE PRESIDENTIAL POPULAR VOTE

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This is Part 3 in a short series projecting which party will win the House in 2020 given different possible presidential outcomes. Because it is a presidential election year and given the intensity of partisanship and increasing number of straight-ticket voters, the presidential results will be the best measure of the national environment and the most important factor in the House elections. This series will explore what those presidential results will mean for the House and which party can expect to win a majority of seats based on the various possibilities. You can find Part 1 here and Part 2 here.

This post is going to complete the series forecasting who will control of the House in 2020 based on the national environment, which is best measured by the presidential popular vote. Democrats currently hold 235 seats, Republicans hold 199, and Justin Amash is the lonely independent in MI-03. This means that Democrats can afford to lose, at most, net 17 seats.  This graphic, from our previous post, shows where we left off and what we still need to finish. 

The next chart shows, according to our model, the order that Democratic held seats would flip to Republicans. The model’s calculation uses the 2018 midterm margin, the changes in incumbency status from 2018 to 2020, and an adjustment for the 7.3% Democratic environment of the 2018 midterms. The last column shows the projected margin for the district in a neutral national environment, with positive numbers indicating a Republican victor and negative numbers indicating a Democratic win. Finally, the districts highlighted in red are ones where Donald Trump won >51% of the vote, which will be important for our projections below.

Safely Democratic
Let’s start with what national environment Democrats need to “Safely” hold the house. As with “Safely Republican”, I am going to build in a lot of safeguards here, setting a high bar for the House to be considered safe. These include:

  • Building in a 10 seat Democratic cushion, meaning that, for this calculation, Democrats can only lose seven seats, putting the House at 228D to 206R.
  • Assuming that Democrats lose the eight districts that Trump won by >51%.1In the “Safely Republican” calculation we assumed that Republicans lost any seat that Clinton won by >50%, not >51% like we assume here. The bar is a bit higher here because 1) There are a lot more seats held by Democrats that Trump won and Democrats are very unlikely to lose all of them. 2) A lot of these seats are in suburban zones that are swinging heavily away from Republicans.

Taking these two precautions, we already have Democrats losing eight seats — one more than our Safe model will allow. This means that they will have to win back one seat. The presidential popular vote they need to be able to expect to win this seat will be the bar they need to clear to Safely control the House.

So which House seat currently occupied by Republicans will be easiest for Democrats to flip? According to our model, the easiest seat for Democrats to flip will be TX-23.

This seat spans a majority of Texas’s western border with Mexico and is 62% Hispanic, a key demographic for Democrats. The Republican incumbent, Will Hurd, has been a uniquely strong incumbent, but barely squeaked out a 0.4% win and is not running for reelection next year. According to our calculation2Start with Republicans’ 0.4% 2018 margin. Adjust in Republicans favor 7.3% for the Democratic leaning environment in the 2018 midterms. Give Democrats a 2.7% boost due to the Republicans losing their incumbency advantage., Republicans could expect to win this seat by 5% in a neutral environment, meaning that Democrats need a 5.1% favorable environment to win this seat and be considered “Safe” to keep control of the House.

Likely Democratic
Moving to the “Likely Democratic” category, we are going to ease up on the safeguards a bit. The precautions now include:

  • Building in a 5 seat Democratic cushion, meaning that, for this calculation, Democrats can only lose 12 seats, putting the House at 223D to 211R.
  • Assume Democrats lose the eight districts where Trump won > 51%.

With these guardrails in place, Democrats can still afford to lose four more seats. The easiest of which (according to our model) would be NM-02, UT-04, CA-39, CA-21. The next seat in line, GA-06, is the one Democrats would need to hold onto. It would be 0.9% R in a neutral environment, meaning Democrats need to have a 1% advantage to make control of the House “Likely Democratic”

Toss Up
For our “Toss-Up” category we are going to find the tipping point seat — the one that would tip control of the House away from Democrats. Given the current breakdown of the House with one independent, there are actually two tipping point seats — one that would tip the House to a 217 – 217 tie and one that would tip it to a 218 – 216 Republican majority. The 18th and 19th seats that Republicans flip are these two “tipping point” seats. The 18th most likely seat to flip is Florida 27th and the 19th most likely is MI-08. These two districts would lean 1.9% and 1.4% Democratic in a neutral national environment, making these the boundaries for the toss up category.

Wrapping Up
Now that we have all the data, we can fill in the rest of our chart.  

A neutral environment, meaning the presidential popular vote is 50/50, falls into the “Lean Democrat” category. This is mostly due to their incumbency advantage in many of the most competitive districts that could determine control of the House. Democrats also have an advantage in the 1-3% margin range. If the national environment is 1%-3.3% in Democrats favor, they are “Likely” to win the House, but if it is a similar Republican leaning environment, the House a Toss Up, Lean Republican and even Lean Democrat. If either party wins by around 5% or more, though, it looks like the House is theirs.

FORECASTING THE HOUSE: WHAT REPUBLICANS NEED TO “LIKELY” WIN CONTROL

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This is Part 2 in a short series projecting which party will win the House in 2020 given different possible presidential outcomes. Because it is a presidential election year and given the intensity of partisanship and increasing number of straight-ticket voters, the presidential results will be the best measure of the national environment and the most important factor in the House elections. This series will explore what those presidential results will mean for the House and which party can expect to win a majority of seats based on the various possibilities. You can find Part 1 here.

Quick Recap
If you did not read Part 1 of the article series, go read it for context. If you did (or are too lazy to go read it), here’s a quick recap. The goal is to determine what the 2020 presidential popular vote will need to be for:

  1. Republicans to be guaranteed to re-take the House
  2. Democrats to be guaranteed to hold the House
  3. Republicans to be likely (but not guaranteed) to re-take the House
  4. Democrats to be likely (but not guaranteed) to re-take the House
  5. Democrats and Republicans to be about equally as likely to control the House.

Last week’s post focused on #1 — what the presidential popular vote margin needs to be to create an environment where Republicans safely win the House. As you can see in the chart below, 4.7% is the end of “Safely Republican” territory and 4.6% is the start of the “Likely Republican” zone. Again, go read Part 1 to see exactly how this was determined.

Calculating the Likely Republican Presidential Popular Vote
Today we are continuing with the Republican side of the arch. What margin do Republicans need in the presidential popular vote to be likely to win the House?

Here are the variables we will take into account:

  • Each district’s 2018 margin. This will be the baseline for the 2020 results.
  • The incumbency advantage. FiveThirtyEight estimates that incumbents have a 2.7% incumbency advantage. So, for candidates who were incumbents before 2018, they will get no additional boost. Candidates who won an open seat, will get this 2.7% boost. Candidates who beat an incumbent in 2018 will get double the 2.7% (5.4%), to account for the incumbency advantage of their opponent that they overcame in that election.
  • Each district’s 2016 presidential vote: We will assume that the Republican loses in any seat in which Clinton won > 50%. These are highlighted in blue.
  • The 2018 midterm’s national environment. Because the environment leaned 7.3% in Democrats’ fav or, this will be subtracted from the Democratic candidate’s margin.

The chart below shows, according to the above variables, which Democratic seats Republicans are most likely to win. For this calculation, we will assume that Republicans win districts exactly in this order. Of course, this is not precisely how things would really play out, but it should, on the whole, represent what Republicans will need to win back these districts.

The districts in which Hillary Clinton won >50% of the vote, and which we therefore assume Democratic congressional candidates will win, are highlighted in blue.  

So, how many seats do Republicans need to win to fit our “Likely Republican” category. I am going to be mildly conservative in this calculation whereas for the “Safely Republican” category, I wanted a number that all but guaranteed a Republican victory, and was therefore extremely conservative. 

Here are the safeguards I am building into the calculation as to what Republicans need in order to “likely” win back the house. You can compare this to the “Safely Republican” safeguards, which were much more conservative. 

  • 5-seat cushion. Meaning I am estimating what Republicans need to win 223 seats, not the bare-majority 218.
  • Assuming that Republicans lose two of the four seats with candidates embroiled in scandal: Steve King (IA-04), Duncan Hunter (CA-50), Chris Collins (NY-27), Ross Spano (FL-15)
  • Assuming that Democrats win every seat where Hillary Clinton won >50% of the vote in 2016.

This means that Republicans will need to flip: 19 to take the majority, + 5 seat cushion + 2 to make up for seats lost due to scandal.  So, Republicans need to flip 19+5+2 = 26 seats.

The 26th seat that Democrats would flip is NY-19, which is north of New York City and encompasses much of the Hudson Valley and the Catskill Mountains.  This seat is currently held by Antonio Delgado, who beat an incumbent by 5.2%. If we adjust for incumbency (+5.4%) and the Democratic environment of 2018 (-7.3%), we find that, in a neutral environment, Delgado could expect to win his district by 3.3%. Therefore, Republican will need a 3.4% lead in the national environment, measured by the presidential popular vote, to likely win the House.

Now we can fill in the rest of the left-half of the graph. I have made a change to the graph to include a “Lean Republican” and “Lean Democrat” rating. This is the range where a party has a slight advantage, but one that could be easily overcome by just a few close districts swinging the wrong way. If Republicans win the presidential vote by in between 4.6% and 3.4%, they are likely, but not guaranteed, to take back the House. Since “Likely Republican” ends at 3.4%, we can fill in 3.3% as the start of the next zone, “Lean Republican”. The arrows indicate where new information was added.

The next post will complete the chart. We’ll calculate presidential popular vote for the Safely Democrat, Likely Democrat, Lean Democrat, Lean Republican and Toss Up categories.

FORECASTING THE HOUSE: WHAT REPUBLICANS NEED TO SAFELY WIN CONTROL

This is Part 1 in a short series projecting which party will win the House in 2020 given different possible presidential outcomes. Because it is a presidential election year and given the intensity of partisanship and increasing number of straight-ticket voters, the presidential results will be the best measure of the national environment and the most important factor in the House elections. This series will explore what those presidential results will mean for the House and which party can expect to win a majority of seats based on the various possibilities.

Sign up for ESY below! We won’t bother you except to let you know about fresh, new content. We promise!


As we get closer to election day, presidential polling will begin to expose the national political environment and how the country feels about the two parties. But because the presidential election is so far away and the Democratic primary is up in the air, the House generic ballot — which asks poll respondents to choose between a generic Republican and generic Democrat for the House — is a better measure of the nation’s feelings on the two parties than presidential polls.

Eventually, taking both of these indicators into account will give the best picture of where House Republicans and Democrats stand. As election day gets closer, I will start relying more heavily on presidential polls and start using the House generic ballot less to measure the national environment and more to understand if voters plan to distinguish between their presidential and congressional votes.

Specifically, the goal of this series is to determine what the presidential popular vote will need to be for:

  1. Republicans to be guaranteed to re-take the House
  2. Democrats to be guaranteed to hold the House
  3. Republicans to be likely (but not guaranteed) to re-take the House
  4. Democrats to be likely (but not guaranteed) to re-take the House
  5. Democrats and Republicans to be about equally as likely to control the House.

By the end of this series, the chart below will be filled. Today, though, the task is to fill in only the bottom-left portion of the graph — the presidential popular vote margin that Republicans will need to safely win control of the House. The percentages around the semi-circle represent margins over the opposing party in the presidential popular vote. 

So, what margin do Republicans need in the presidential popular vote to safely win control of the House? Heading into the 2020 elections, Republicans will need to net at least 19 seats to win back the House. The current makeup of the House is 235 Democrats, 197 Republicans, one independent and two vacancies. One of these vacancies, NC-03, is a safe Republican seat, meaning Republicans effectively have 198 seats. The other vacancy, is NC-09, will have a special election next week due to election fraud tainting the 2018 election. Lastly, the independent is Justin Amash in MI-03, who renounced his Republican identity after clashing with Trump and the party after calling for impeachment.

I am going to be extremely conservative in this calculation, because I want a number that will ensure Republicans control of the House barring wild circumstances.

As I’m being very conservative, I’m going to build in a lot of room for error on the Republican side. The safeguards are:

  • A 10-seat cushion. Meaning I am estimating what Republicans need to win 228 seats, not the bare-majority 218.
  • Assuming that Republicans lose the four seats with candidates embroiled in scandal: Steve King (IA-04), Duncan Hunter (CA-50), Chris Collins (NY-27), Ross Spano (FL-15)
  • Assuming that Democrats win every seat where Hillary Clinton won >50% of the vote in 2016.

Totaling these, in order to reach the “safe” zone, Republicans need to win 33 additional seats: 19 to take the majority + 10 seat cushion + 4 to make up for seats lost due to scandal.

To find out which 33 seats will be easiest for Republicans to flip, we will take several things into consideration. The presidential popular vote that Republicans will need to take that 33rd seat will be our margin for them to “safely” take the House.

Here are the variables we will take into account:

  • 2018 margin. This will be the baseline for the 2020 results.
  • Incumbency advantage. FiveThirtyEight estimates that incumbents have a 2.7% incumbency advantage. So, for candidates who were incumbents before 2018, they will get no additional boost. Candidates who won an open seat, will get this 2.7% boost. Candidates who beat an incumbent in 2018 will get double the 2.7% (5.4%), to account for the incumbency advantage of their opponent that they overcame in that election.
  • 2016 Presidential Vote: Again, we will assume that the Republican loses in any seat in which Clinton won > 50%. These are highlighted in blue.
  • The 2018 midterm’s national environment. Because the environment leaned 7.3% in Democrats’ favor, this will be subtracted from the Democratic candidate’s margin.

The chart below shows, in order, which Democratic seats Republicans are most likely to win, given our conditions and assumptions. The districts highlighted in blue are ones in which Hillary Clinton won >50%, which this overly-cautious projection model assumes that Democrats will win. 

The 33rd seat that Democrats would flip is TX-32 in northeastern Dallas County. This seat is currently held by Collin Allred, who beat an incumbent by 6.5%. If we adjust for incumbency (+5.4%) and the Democratic environment of 2018 (-7.3%), we find that, in a neutral environment, Allred could expect to win his district by 4.6%. Therefore, Republican will need a 4.7% lead in the national environment, measured by the presidential popular vote, to safely win the House.

Keep in mind how many safeguards were build into this: a 10 seat margin, assuming Republicans lose four incumbent-held seats due to scandal and giving Democrats every district where Clinton won >50%. Therefore, if Republicans clear the 4.7% hurdle, they have the House all but guaranteed in the bag.

So, now we can fill in the first part of our chart! The arrow points to the newly filled in projection. We know that Republican’s will take the House (barring something crazy) if they win the presidential popular vote with anywhere between a 100% margin and a 4.7% margin.

The next few weeks will be dedicated to filling in data for the rest of the chart, which will become more useful as the presidential election nears and the national environment starts to become clear.