Recent polling mistakes have been criticized in many ways, particularly after the 2016 election. But polling tends to favor the Democrats and some politicos have found surprising results in many races over the past decade.

However, if you are paying attention to the polling right away, there may be signs that the same mistakes that overinflated Democrats’ confidence in past elections might be repeating themselves.

The New York Times polling analyst Nate Cohn has published a piece this morning that skewers Democrats’ hopes of keeping the Senate.

We created a website to track the latest polls ahead of the 2016 presidential election. It was called a “polling diary” internally. A table that shows what would happen if 2020 polls are as flawed as those in 2016. In 2016, pollsters had systematically underestimated Donald J. Trump’s strength against Hillary Clinton.

This poll error table was created because we noticed early in the 2020 cycle that Joe Biden seemed more successful than Mrs. Clinton in places where polls had overestimated her four years earlier. This pattern did not necessarily indicate that the polls were wrong. It could simply have been a sign of Mr. Biden’s promise strength among white working-class voters.

This warning sign is flashing once again: Democratic Senate Candidates are outrunning expectations in places where polls overestimated Mr. Biden in 2020 and Mrs. Clinton in 2016.

Cohn points out Wisconsin looks very attractive to Democrats at the moment, with incumbent Senator Ron Johnson in serious trouble. He then explained that Wisconsin was the “ground zero” of polling errors in 2020. The strength of Biden was 8 percent higher in polls that were conducted during the presidential election cycle.

Cohn says, “It raises doubts that Wisconsin’s apparent Democratic strength is real.” “A result of unaddressed biases in survey research.”

This makes it very difficult to predict the outcome of the Senate election. Georgia polling is showing Herschel Walker as the clear favorite over Democratic Sen. Raphael Warnock. Even more concerning, Sen. Catherine Cortez Masto from Nevada could lose to Republican challenger Adam Laxalt.

NEW: Sen. Cortez Masto in real trouble of losing her seat in Nevada to Republican Adam Laxalt.

After months of significantly outspending Laxalt, the two remain within the margin of error.

w/ @sahilkapur https://t.co/rJTSmDK6Um

— Natasha Korecki (@natashakorecki) September 12, 2022

Arizona is a traditionally red state, but Sen. Mark Kelly will be fighting for his career against Blake Masters. Although Kelly is currently polling higher in Arizona, Cohn’s data indicates that Arizona underestimated Biden’s support for the state in 2020. Pennsylvania was also affected by the battle for a vacant seat. John Fetterman and Mehmet Oz are fighting for it.

Even if Pennsylvania falls in favor of Democrats, the GOP can win any two other seats to take control of the Senate. Cohn’s analysis could be correct and the GOP could win all three.

Why is this happening?

It won’t be difficult to explain why the polls are incorrect once again. The majority of pollsters have not made any significant changes to their methods since the last election. Post-mortem, the major polling communities declared it impossible to determine what went wrong in 2020.

However, the pattern of Democratic strength doesn’t mean that polls are still in a similar state. Some pollsters claim that they are seeing signs of nonresponse bias in their surveys since the Supreme Court’s Dobbs abortion decision. This is when respondents to a poll are significantly different from those who respond.

Brian Stryker is a partner in Impact Research (Mr. Biden was a client). He told me that his firm was receiving “a lot of Democratic responses” in recent polls, particularly in “the familiar areas” where polls have erred in previous cycles.

Although it’s not certain that polling will be as flawed as in the past, the signs are there. This is a severe warning to Democrats who believe that they are experiencing a surge in polling due to the Dobbs decision, and other legislative wins for their party. Cohn warns that it could be a mirage.