So How Did The Pollsters Do? They Underestimated Republicans, Again.

Representative Ron DeSantis, Republican candidate for governor of Florida, right, speaks as his wife Casey DeSantis, center, and U.S. President Donald Trump look on during a campaign rally in Estero, Florida, U.S., on Wednesday, Oct. 31, 2018.
Jayme Gershen/Bloomberg via Getty Images

In the last few days before the "most important midterm elections in history," pollsters and analysts began to backpedal on their predictions about the much-hyped Blue Wave, which turned out to be merely a solid win in the House and a true Blue Wipe-out in the Senate. On Monday, Politico provided some quotes from pollsters warning the public that "this is no normal election" and suggesting that many of the polls might've failed to calibrate for some unprecedented factors, including a "staggering" early voting turnout and a surge in "non-usual" voters.

So, with the dust settling, how did pollsters do in some of the key races? In short, they generally underestimated Republican support, again.

After crunching all the most recent polling data, Nate Silver's FiveThirtyEight predicted on election morning that Republicans would end up with 52 seats in the Senate and Democrats would most likely secure 234 seats. Both estimates appear to err slightly on the side of Democrats. Republicans are currently poised to end up with 53 and possibly even 54 seats, depending on how Arizona and Colorado shake out (Republicans currently have a slight edge in both with 99% and 84% reporting, respectively). Democrats did make major gains in the House, but appear likely to fall short of Silver's prediction.

More notable than the overall number of seat wins and losses is the percentages by which Republicans defeated Democrats in some key races, particularly in the "toss-up" Senate and gubernatorial races, which garnered the most national attention. Below is a comparison of some of the polling predictions vs. the electoral results in some key Senate and gubernatorial races.

Florida Governor Race

A vast majority of the polls predicted that the Democratic gubernatorial candidate Tallahassee Mayor Andrew Gillum would win by anywhere from 4 to 7 points over Republican Ron DeSantis. Election morning, Real Clear Politics' average of the key polls showed Gillum ahead of DeSantis by 3.6 points. The Daily Wire reports:

Quinnipiac's poll of 1,142 likely voters (conducted 10/29-11/4) gave Gillum a comfortable 7-point advantage. A HarrisX poll of 1,400 likely voters conducted over the same period found Gillum leading by 4 points. An Emerson poll of 748 likely voters (conducted 11/1-3) gave the Democrat a 5-point edge, as did St. Pete Polls' survey of 3,088 likely voters (conducted 11/3-4). Only one of the polls factored into Real Clear Politics' average gave DeSantis an advantage: Republican polling firm Trafalgar Group polled 1,484 likely voters during the final two days before the election and found DeSantis with a 3-point lead.

Gillum ended up losing by 1 point to DeSantis. NBC News lists the current vote count at 99% reporting, DeSantis earning 4,052,246 and Gillum garnering 3,996,906, a 55,340-vote difference.

Florida Senate Race

According to pollsters, incumbent Democrat Sen. Bill Nelson was supposed to defeat Republican Gov. Rick Scott. Real Clear Politics' final average gave Nelson a 2.4% lead over Scott, with polls showing him leading by anywhere from 2 to 7 points: "Quinnipiac's final poll showed Nelson up by 7 points; HarrisX found Scott leading by 2; Emerson gave Nelson a 5-point advantage; St. Pete Polls gave the incumbent a 4-point lead; and Trafalgar Group showed Scott with a slim 2-point edge."

But, as with the Gillum-DeSantis contest, the Republican Trafalgar Group ended up being the only one that got the apparent victor correct. With 99% reporting and Scott beating Nelson 50.2 - 49.8, Scott has declared victory.

Indiana Senate Race

Sen. Joe Donnelly was another incumbent Democrat that most pollsters believed would defeat Republican challenger Mike Braun, and by as much as 7 points: "Real Clear Politics' final average gave him a slim 1.3% advantage over Republican Mike Braun. The final poll by CBS News/YouGov found Braun up by 3 points; NBC News/Marist found Donnelly leading by 2 points; Fox News found Donnelly ahead by 7 points; and the most recent poll, by HarrisX, found Braun with a razor-thin 1-point edge."

Braun has been declared the winner by a sizable margin. With 93% reporting, Braun leads Donnelly by around 10 points, 52.9 - 43.

Missouri Senate Race

While some pollsters did end up giving Republican Attorney General Josh Hawley an edge over incumbent Democrat Sen. Claire McCaskill, only Trafalgar Group (again) got close to predicting his significant 6-point margin. With 99% reporting, Hawley leads McCaskill by 51.5 - 45.5.

RCP's final average gave Hawley a razor-thin 0.6% edge, with three of the six most recent polls showing them tied, NBC News/Marist giving McCaskill a 3-point lead, Trafalgar Group showing Hawley up by 4, and Emerson giving him a 3-point advantage.

Montana Senate Race

With 95% reporting, Republican Matt Rosendale leads incumbent Democrat Jon Tester 48.8 - 48.3. On election morning, RCP gave Tester a 3.3-point advantage: "Gravis's final poll gave Tester a 3-point lead; HarrisX gave him a 6-point lead; and Trafalgar Group gave him just a 1-point edge over Rosendale." Once again, Trafalgar Group got the closest.

Tennessee Senate Race

While most pollsters accurately predicted Republican Marsha Blackburn would defeat Democrat Phil Bredesen (despite Taylor Swift's endorsement), all of them underestimated the size of the victory. With 99% reporting, Blackburn leads Bredesen by about 11 points, 54.7 - 43.9. On election morning, RCP gave her a 5.2-point advantage, with CNN showing her ahead by 4, Fox News by 9, and Emerson by 8.

North Dakota Senate Race

Similar to the Tennessee race, pollsters likewise correctly gave Republican Kevin Cramer the advantage over incumbent Democrat Sen. Heidi Heitkamp, but underestimated the size of his victory. RCP's final average was a 9-point lead for Cramer, with both Trafalgar Group and Fox News showing him the same advantage. With 99% reporting, Cramer holds an 11-point lead over Heitkamp, 55.4 - 44.6.

West Virginia Senate Race

As with the Tennessee race, pollsters slightly underestimated Republican support in the contest between incumbent Democrat Joe Manchin and Republican Patrick Morissey. Manchin won by 3.2 points, 49.5 - 46.3. On election morning, RCP gave Manchin a 5-point lead by average, both MetroNews and Emerson giving him that same advantage.

Not all of the polling data underestimated Republicans; in a few races, pollsters missed the mark going the other direction. Democrat Jacky Rosen defeated incumbent Republican Sen. Dean Heller by over 3 points, 49.7 - 46, in the Nevada Senate race. Polling data showed the two tied on the morning of the election. Likewise, incumbent Republican Sen. Ted Cruz was supposed to skate to victory in the Texas Senate race, polling data giving him a 6.8-point lead heading into the election. He ended up only winning by only about 2.6 points, 50.9 - 48.3.

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