Did the COVID-19 pandemic doom Trump's reelection? Our early analysis, which examines change in county-level share of votes between 2016 and 2020, suggests that COVID-19 played a key role in Trump's defeat. We found that voters living in counties with a high number of COVID-19 cases were less likely to vote for Trump, particularly in urban counties and in swing states.

All things being equal, Donald Trump would likely have won re-election if COVID-19 cases had been between 5 and 10 percent lower. In particular, Arizona, Georgia, Pennsylvania, and Wisconsin, which President-Elect Biden won by a slim margin, would have remained red. We also found that the difference in total number of votes in each county – which we use as a rough proxy of turnout – was positively impacted by the pandemic, though the empirical evidence is not conclusive. All in all, our results suggest that some of Trump's voters switched to Biden because of the pandemic.

These findings challenge initial press analyses suggesting that counties with worst virus surges overwhelmingly voted for Trump. A closer look at them reveals that they missed a key source of statistical bias: partisan identity tends to drive virus mitigation efforts and Trump support. Indeed, several national polls and academic studies show that Trump's voters are significantly less likely to wear masks and complying with social distancing, which in turn increases the probability of outbreaks.

By contrast, our results show that how our political leaders handle or mishandle crises matters to voters. We found that counties with more COVID-19 cases had decreased electoral support for Trump, particularly in in urban counties, in swing states, and in states that he won in 2016. The strong results in urban counties are likely driven by suburban areas, where Trump performed much better in 2016 than he did in 2020.

So why did voters switch from Trump to Biden? There are at least two possible explanations. On one hand, voters may have punished Trump for how he handled COVID-19. Prior to the pandemic, the U.S. economy was performing well, and Trump, while extremely polarizing, enjoyed strong support among Republican voters. But the virus changed the narrative, and Trump's response was widely criticized as he downplayed the risks of the disease, refused to embrace basic health precautions such as wearing masks, and repeatedly criticized epidemiologists and scientists, including those advising him.

On the other hand, some voters may have switched from Trump to Biden as a result of changes to their policy preferences triggered by the pandemic. There is strong evidence, for instance, that people growing up in a recession are more likely to favor state intervention and large social welfare programs. We believe the severe public health threat and major economic losses may have shifted preferences in favor of a stronger social safety net, like healthcare and unemployment insurance programs. Since the Democratic Party and its presidential candidate are more likely to champion these policies, it may have reaped the benefits of this switch in voters' preferences.

As recounts are underway in some states, it remains to be seen how this year's record-high voter turnout influenced these dynamics. Both presidential candidates would have won any previous elections, given the sheer number of votes at the national level. Nevertheless, one thing remains clear: voters are watching as their leaders wade through the COVID-19 crisis and are looking to see if they will sink or swim.

Leonardo Baccini is an associate professor of political science at McGill University and a National Fellow at the Hoover Institution (Stanford University) for the 2020-21 academic year, Abel Brodeur is an associate professor of economics at University of Ottawa, and Stephen Weymouth is an associate professor of business at Georgetown University.