Republicans Need A Systematic Polling Error To Win The House

As I wrote earlier this week, Democrats almost certainly need a systematic polling error to win the Senate. By that I mean: They need for the polls to be off everywhere, or at least in certain key clusters of states, to win the Senate. A polling error in just one or two races (say, Beto O’Rourke wins in Texas) probably wouldn’t be enough: Democrats are defending too much territory and have too many problems elsewhere on the map just to get lucky.

That conclusion about the Senate ought to be fairly intuitive, I think. Even if you credit Democrats with wins in all the toss-up races, that wouldn’t be enough — it would only get them to 50 seats. What might be more surprising is that the same conclusion holds for Republicans in the House. They need for there to be a systematic polling error too. If the polls are about right overall but Republicans are hoping to getting lucky in the swing districts, it probably won’t happen — the odds are stacked heavily against them.

The reason it’s counterintuitive is because you can’t really identify 23 districts that are safe bets to flip to Democrats (that’s the number they need to take the House). In the Deluxe version of our model (the one I’ll be focusing on here), only 193 seats are considered to be “solid Democratic” (at least a 95 percent chance of a Democratic victory). If Democrats won only those seats and no others, they’d actually lose two seats from the 195 they control now. Another 15 seats are “likely Democratic,” where Democrats have at least a 75 chance of winning. Win those as well, and Democrats are … still up to a net gain of only 13 seats.1

The model then has 34 seats in its three most competitive categories: “lean Democratic” (eight seats), “toss-up” (16 seats) and “lean Republican” (10 seats). If Republicans win 24 of those 34 seats — assuming everything else goes to form — they’ll keep the House.

How hard is that? Because of the possibility of a systematic polling error, it isn’t really that hard at all. If there’s a typical polling error of 2 to 3 percentage points and it works in Republicans’ favor, the House would be a toss-up. We might not even know the winner for several days as everyone waits for additional mail ballots to be returned from California. Thus, the Lite forecast gives Republicans a 2 in 9, or 22 percent, chance of keeping the House based on the possibility of a systematic polling error. Their chances are 18 percent in Deluxe and 15 percent in our Classic version, meanwhile.

That isn’t a great position, but those are real, tangible chances.

Without the possibility of a systematic polling error, however, the GOP’s position is nearly hopeless. If all races were independent from one another and GOP chances in the most competitive races were approximately 50-50, the Republicans would have to do the equivalent of have a coin come up heads at least 24 times in 34 attempts. That’s really hard. The probability of ending up with at least 24 heads in 34 tries is only about 1 in 80.

We can also come up with a more sophisticated version of this coin-flip calculation. Instead of putting the races into different buckets and treating them as 50-50, we can just use the probabilities listed by the Deluxe model in each of the 435 districts — that Republicans have an 83 percent chance of winning New York 24, for example. We can run a Monte Carlo simulation to see how often Republicans wind up with at least 218 seats. The answer is that, assuming that races are independent — again, a bad assumption, but what you get in a world in which there isn’t systematic polling error — Republican chances of holding the House are only about 1 in 1,000.

What if we use the Lite version of our calculations instead? Lite is essentially a “polls-only” forecast; it uses district-level polls in districts where it has enough of them and national (generic congressional ballot) polls and polls of similar districts to make inferences in districts where it doesn’t. If you run a Monte Carlo simulation with our Lite forecast — assuming that each district is independent — Republican chances aren’t much better, about 1 in 700.

But why is it so hard for Republicans to win the House without a systematic polling miss? The short answer is because they’re defending too much territory: The House playing field is exceptionally broad this year, because of Republican retirements, an influx of Democratic cash and other factors. The decisive race won’t necessarily be in a toss-up district; it could very easily be in a “likely Republican” district where a GOP incumbent is caught sleeping at the wheel (perhaps a district where there hasn’t been much polling).

To help illustrate the breadth of the playing field, I’ve sorted every House district based on the projected margin of victory or defeat for the Democratic candidate, according to the Deluxe model, and ordered them from No. 1 (the easiest seat for Democrats to win) to No. 435. Except, I’m only going to show you the districts in the middle of the spectrum; everything from district No. 190 (if Democrats won only 190 districts, they’d lose a net of five House seats) to No. 295 (a net gain of 100 seats).2

The 105 seats that will decide the House

Net change to the current distribution of the House if Democrats win that district and every other district with a greater chance of a Democratic victory

Rank
District
Dem. Candidate
GOP Candidate
Deluxe Margin
Net Change




190
MN-7
Collin Peterson
Dave Hughes
12.7
R+5


191
PA-8
Matt Cartwright
John Chrin
11.0
R+4


192
PA-17
Conor Lamb
Keith J. Rothfus
10.7
R+3


193
AZ-2
Ann Kirkpatrick
Lea Marquez Peterson
10.4
R+2


194
CA-49
Mike Levin
Diane L. Harkey
9.9
R+1


195
IA-1
Abby Finkenauer
Rod Blum
9.8
—


196
PA-7
Susan Ellis Wild
Martin W. Nothstein
9.7
D+1


197
AZ-1
Tom O’Halleran
Wendy Rogers
9.1
D+2


198
NV-4
Steven Horsford
Cresent Hardy
7.9
D+3


199
NH-1
Chris Pappas
Eddie Edwards
7.8
D+4


200
FL-27
Donna Shalala
Maria Salazar
7.7
D+5


201
VA-10
Jennifer Wexton
Barbara Comstock
7.1
D+6


202
NJ-11
Mikie Sherrill
Jay Webber
7.1
D+7


203
CO-6
Jason Crow
Mike Coffman
7.0
D+8


204
KS-3
Sharice Davids
Kevin Yoder
6.7
D+9


205
MN-2
Angie Craig
Jason Lewis
6.2
D+10


206
MN-3
Dean Phillips
Erik Paulsen
6.1
D+11


207
MI-11
Haley Stevens
Lena Epstein
5.2
D+12


208
NV-3
Susie Lee
Danny Tarkanian
5.0
D+13


209
NJ-7
Tom Malinowski
Leonard Lance
3.4
D+14


210
CA-10
Josh Harder
Jeff Denham
3.3
D+15


211
IA-3
Cindy Axne
David Young
2.2
D+16


212
CA-45
Katie Porter
Mimi Walters
2.2
D+17


213
NY-19
Antonio Delgado
John J. Faso
2.1
D+18


214
WA-8
Kim Schrier
Dino Rossi
1.9
D+19


215
IL-6
Sean Casten
Peter J. Roskam
1.9
D+20


216
CA-48
Harley Rouda
Dana Rohrabacher
1.8
D+21


217
CA-25
Katie Hill
Stephen Knight
1.7
D+22


218*
ME-2
Jared Golden
Bruce Poliquin
1.6
D+23


219
MI-8
Elissa Slotkin
Mike Bishop
1.4
D+24


220
KS-2
Paul Davis
Steve Watkins
1.4
D+25


221
NJ-3
Andy Kim
Tom MacArthur
1.0
D+26


222
CA-39
Gilbert Cisneros
Young Kim
0.9
D+27


223
NY-22
Anthony J. Brindisi
Claudia Tenney
0.7
D+28


224
UT-4
Ben McAdams
Mia B. Love
0.6
D+29


225
MN-1
Dan Feehan
Jim Hagedorn
0.6
D+30


226
NC-9
Daniel McCready
Mark Harris
0.5
D+31


227
KY-6
Amy McGrath
Andy Barr
0.2
D+32


228
FL-26
D. Mucarsel-Powell
Carlos Curbelo
-0.1
D+33


229
TX-7
Lizzie Fletcher
John Culberson
-0.2
D+34


230
VA-7
Abigail Spanberger
David Brat
-0.3
D+35


231
NM-2
Xochitl T. Small
Yvette Herrell
-0.6
D+36


232
PA-1
Scott Wallace
Brian K. Fitzpatrick
-0.7
D+37


233
FL-15
Kristen Carlson
Ross Spano
-1.8
D+38


234
NC-13
Kathy Manning
Theodore Paul Budd
-2.2
D+39


235
OH-12
Danny O’Connor
Troy Balderson
-2.2
D+40


236
IL-14
Lauren Underwood
Randy Hultgren
-2.3
D+41


237
VA-5
Leslie Cockburn
Denver Riggleman
-2.4
D+42


238
TX-32
Colin Allred
Pete Sessions
-3.0
D+43


239
NE-2
Kara Eastman
Don Bacon
-3.1
D+44


240
GA-6
Lucy McBath
Karen Handel
-3.1
D+45


241
VA-2
Elaine G. Luria
Scott W. Taylor
-3.3
D+46


242
PA-10
George B. Scott
Scott Perry
-3.9
D+47


243
MT-1
Kathleen Williams
Greg Gianforte
-4.1
D+48


244
IL-12
Brendan F. Kelly
Mike J. Bost
-4.5
D+49


245
IL-13
Betsy Londrigan
Rodney Davis
-4.6
D+50


246
FL-6
Nancy Soderberg
Michael Waltz
-4.8
D+51


247
MI-7
Gretchen Driskell
Tim Walberg
-4.9
D+52


248
NY-27
Nate McMurray
Chris Collins
-5.0
D+53


249
CA-50
A. Campa-Najjar
Duncan Hunter
-5.1
D+54


250
NY-11
Max Rose
Dan Donovan
-5.3
D+55


251
WI-1
Randy Bryce
Bryan Steil
-5.4
D+56


252
WA-3
Carolyn Long
Jaime Herrera Beutler
-5.4
D+57


253
OH-1
Aftab Pureval
Steve Chabot
-5.8
D+58


254
WA-5
Lisa Brown
C. McMorris Rodgers
-5.9
D+59


255
NY-24
Dana Balter
John Katko
-6.3
D+60


256
AK-1
Alyse S. Galvin
Don Young
-6.3
D+61


257
TX-23
Gina Ortiz Jones
Will Hurd
-6.4
D+62


258
NC-2
Linda Coleman
George Holding
-6.4
D+63


259
MN-8
Joe Radinovich
Pete Stauber
-6.5
D+64


260
GA-7
Carolyn Bourdeaux
Rob Woodall
-6.9
D+65


261
AZ-8
Hiral Tipirneni
Debbie Lesko
-7.0
D+66


262
IA-4
J.D. Scholten
Steve King
-7.0
D+67


263
MI-6
Matt Longjohn
Fred Upton
-7.2
D+68


264
FL-16
David Shapiro
Vern Buchanan
-7.6
D+69


265
WI-6
Dan Kohl
Glenn Grothman
-7.6
D+70


266
CA-21
TJ Cox
David Valadao
-7.6
D+71


267
PA-16
Ronald A. DiNicola
Mike Kelly
-7.8
D+72


268
AR-2
Clarke Tucker
French Hill
-7.9
D+73


269
FL-18
Lauren Baer
Brian Mast
-8.0
D+74


270
NY-2
Liuba Shirley
Peter King
-8.2
D+75


271
CA-4
Jessica Morse
Tom McClintock
-8.3
D+76


272
OH-14
Betsy Rader
David Joyce
-8.3
D+77


273
FL-25
Mary Barzee Flores
Mario Diaz-Balart
-8.3
D+78


274
TX-21
Joseph Kopser
Chip Roy
-8.3
D+79


275
MO-2
Cort VanOstran
Ann Wagner
-8.8
D+80


276
TX-22
Sri Kulkarni
Pete Olson
-9.0
D+81


277
NY-23
Tracy Mitrano
Thomas Reed
-9.4
D+82


278
CO-3
Diane Mitsch Bush
Scott Tipton
-9.4
D+83


279
SC-1
Joe Cunningham
Katie Arrington
-9.6
D+84


280
WV-3
Richard Ojeda
Carol Devine Miller
-9.8
D+85


281
OK-5
Kendra Horn
Steve Russell
-10.0
D+86


282
IN-9
Liz Watson
Trey Hollingsworth
-10.2
D+87


283
CA-1
Audrey Denney
Doug LaMalfa
-10.6
D+88


284
TX-31
Mary J. Hegar
John R. Carter
-10.8
D+89


285
TX-2
Todd Litton
Dan Crenshaw
-10.9
D+90


286
NC-8
Frank McNeill
Richard Hudson
-11.0
D+91


287
NY-21
Tedra Cobb
Elise Stefanik
-11.2
D+92


288
NY-1
Perry Gershon
Lee Zeldin
-11.3
D+93


289
OH-10
Theresa Gasper
Michael R. Turner
-11.5
D+94


290
AZ-6
Anita Malik
David Schweikert
-11.6
D+95


291
MI-1
Matt Morgan
Jack Bergman
-11.9
D+96


292
NC-7
Kyle Horton
David Rouzer
-12.1
D+97


293
CA-22
Andrew Janz
Devin Nunes
-12.3
D+98


294
OH-7
Ken Harbaugh
Bob Gibbs
-12.9
D+99


295
IN-2
Mel Hall
Jackie Walorski
-13.1
D+100

* The tipping-point district (the one that would give Democrats a 218-217 majority).

This table excludes the seats least likely to change hands. Based on FiveThirtyEight Deluxe model as of 11:30 p.m. on Nov. 2

If you know these districts pretty well, you can keep scrolling down the list until you tap out and say, “No, that’s too much for me.” For me, you get pretty far down the list before that happens. The 240th district, for example, which would correspond to a Democratic gain of 45 seats, is Georgia 6 — that’s the district where Democrat Jon Ossoff lost in a special election last year but where Lucy McBath has a decent shot because of the potential for higher black turnout. Chris Collins’s district is at No. 248, and Duncan Hunter’s is at 249. Alaska’s at-large district, where Democratic candidate Alyse Galvin actually had a tiny lead in the latest poll, is at No. 256. Steve King’s district is at No. 262. It’s about at that point that we get into upsets that I’d consider really far-fetched, but even then, there are a few interesting races. West Virginia 3, where Democrat Richard Ojeda has sometimes been competitive in polls despite it having voted overwhelmingly for Trump, is No. 280.

Democrats are underdogs in most of these districts individually, but they’re overwhelming favorites to win some of these districts or others like them on the list — unless the polls were wrong all along and were exaggerating the potential for a “blue wave.”