Recall in 2016 that the national polls were quite accurate (Hillary Clinton won the popular vote by more than two points), while the state polls, albeit some within the margin of error, gave the impression of a narrow but definitive Clinton win. There was much talk about a quiet base of Trump voters embarrassed to say they support him, but in fact, 80,000 votes going the other way would have made Clinton president. (I know. Don’t dwell.) This time around, there is reason to believe we will have all mail-in or heavily mail-in voting in many states. The access to those ballots and the propensity of various groups to use them might be different. In other words, defining “likely” voters is trickier than you think.
Moreover, the “Who knows?” interpretation of polls posits that lots can happen in four months, so Trump’s chances might improve. (That last part is beginning to fail the straight-face test, as Trump’s performance continues to deteriorate daily and the pandemic worsens.)
The alternative theory goes like this: Even if the polls are off, they cannot be that far off. Biden is winning nationally by an average of nearly 9 points (just today Economist-YouGov, a respected, nonpartisan poll, gives him a 9-point lead, and Quinnipiac shows him with a stunning 15-point lead). The big deficit for Trump tracks with his approval rating (one of the best indicators of an incumbent’s election percentage), which has dropped below 40 in several recent polls. Biden is also crushing it in swing states such as Pennsylvania (leading by an eye-popping 13 points in Monmouth’s most recent poll) and is competitive or slightly ahead in states no Democrat has thought competitive in the past decade or so (e.g., Arizona and Texas). Finally, polling for Senate seats shows a tilt toward Democrats even in red states (e.g., Montana and Arizona), giving support to the “blue tsunami” interpretation of the race.
Many Democratic operatives believe the second theory is right but are frankly spooked by 2016 and afraid to say it out loud. Campaigning 101 also says that you should tell your staff, donors and voters to think you are three points behind. The trauma of 2016 and fear of overconfidence have not dissipated. On the other side, Republicans face their own dilemma. At some point, they will have to decide whether they want to effectively give up on Trump. (Labor Day might be too late given the plethora of early voting, which starts, for example, on Sept. 19 in Michigan.) Donors will decide whether to throw money into a hopeless campaign; candidates for Senate and House will begin the ads arguing to not give Biden a “blank check.”
The safest answer would be something like this: If the election were held today, it would be a big win for Biden, and while Trump is unlikely to undergo a believable personality transformation and the coronavirus pandemic might possibly — if we are fortunate — be less terrible than now, it is also possible Trump has not hit rock bottom yet. In other words, act like Biden is three points down.