As the 2022 midterm election nears, polls increasingly indicate that Democrats will be more competitive than previously thought. The red tsunami, which once looked menacing, now appears to be nothing more than a small ripple.
But polling expert Nate Cohn explained this week a key "warning sign is flashing again," suggesting polls are overestimating Democrats' prospects.
What are the details?
Jen Psaki, the former White House press secretary turned MSNBC employee, claimed Tuesday that election forecasts have "flipped," now showing Democrats in the driver's seat less than two months from Election Day.
Indeed, polls are increasingly showing Democrats may not lose control of the Senate and potentially even the House. But those polls do not tell the whole story.
Cohn wrote in the New York Times that ahead of the 2020 presidential election, Joe Biden was outperforming then-President Donald Trump in many of the same regions of the country where polls overestimated support for Hillary Clinton in the 2016 presidential election.
Such overestimation in favor of Democrats appears to be happening again.
"That warning sign is flashing again: Democratic Senate candidates are outrunning expectations in the same places where the polls overestimated Mr. Biden in 2020 and Mrs. Clinton in 2016," Cohn wrote.
Cohn highlighted one Senate race in particular — Republican Sen. Ron Johnson's battle against Democrat Mandela Barnes in Wisconsin — as a potential bellwether for bad polling after a recent Marquette Law School poll showed Barnes leading Johnson by a significant margin of 7 points.
But in this case, good for Wisconsin Democrats might be too good to be true. The state was ground zero for survey error in 2020, when pre-election polls proved to be too good to be true for Mr. Biden. In the end, the polls overestimated Mr. Biden by about eight percentage points. Eerily enough, Mr. Barnes is faring better than expected by a similar margin.
The Wisconsin data is just one example of a broader pattern across the battlegrounds: The more the polls overestimated Mr. Biden last time, the better Democrats seem to be doing relative to expectations. And conversely, Democrats are posting less impressive numbers in some of the states where the polls were fairly accurate two years ago, like Georgia.
When Cohn plotted the places where polls overestimated Democrats, he discovered a "consistent link between Democratic strength today and polling error two years ago."
What is causing the error?
According to Cohn, "persistent and unaddressed biases" in survey methodology — like nonresponse bias — is causing pollsters to derive misleading polls.
What this means practically, he explained, is that what appears to be Democratic strength in the run-up to the election could actually be nothing more than a "mirage."
If the same polling errors from previous elections persist this year, Republicans will handily win the House and could even take control of the Senate.