The coronavirus has quickly become a highly politicized election-year issue.

Democrats have criticized President Trump for reacting slowly to the crisis, for contradicting the advice of his health experts and for spreading misinformation about the virus. Trump has countered by accusing Democrats and the news media of exaggerating health risks to hurt his reelection campaign.

The American public’s views about the coronavirus are polarized along partisan lines as well. Democrats were more than three times as likely to be “very concerned” about the virus than Republicans in the latest YouGov-Economist poll (43 percent to 12 percent, respectively). Twice as many Democrats as Republicans said the coronavirus poses an “imminent threat” in a recent Ipsos-Reuters survey.

It’s not surprising that Republicans are minimizing the coronavirus threat. Political science research highlights three ways that a pandemic could undermine support for the president

It’s the economy, stupid

The economic impact of the coronavirus poses the clearest risk to the president’s reelection campaign. The epidemic has already spooked the stock market and sparked fears of a global recession. Goldman Sachs projected that because of the coronavirus, the U.S. economy would grow by only 0.9 percent during the first three months of 2020 and not grow at all during the second quarter.

The economy has historically loomed large in presidential elections, so an economic downturn probably would hurt Trump’s reelection prospects. In presidential contests from 1948 to 2016, every percentage point increase/decrease in election-year gross domestic product growth per capita is associated with about a two- to three-percentage-point increase/decrease in the incumbent party’s vote share.

If that relationship holds in 2020, a coronavirus slowdown could easily swing the election. Even if the outbreak’s effects on economic growth are not as severe as most economists fear, any economic slump could tilt a close election away from the president.

In fact, an election-year downturn threatens to overshadow all of the positive economic indicators over the first three years of Trump’s presidency. Numerous studies show the election-year economy influences presidential election results far more than cumulative growth throughout the term.

It’s unlikely to matter, either, that the president bears little responsibility for a global economic slowdown caused by the coronavirus. Christopher Achen and Larry Bartels’s theory of “blind retrospection” suggests voters will reward or punish presidents for short-term changes in the election-year economy regardless of why they happened.

Now, Trump could be somewhat insulated from an economic downturn because public opinion about his presidency has been more divorced from the country’s economic performance than it was for previous presidents. But presidents running for reelection in growing economies have been very difficult to defeat, especially when they campaign heavily on their economic accomplishments.

By all accounts, President Trump was planning to run for reelection on the economy. The coronavirus’s economic effect threatens his strongest campaign message.

Performance matters

Studies suggest presidents are punished for conditions beyond their control such as natural disasters. But presidential performance still matters.

Take, for example, President George W. Bush’s and President Barack Obama’s respective responses to Hurricane Katrina and Hurricane Sandy. Bush was widely criticized for his slow response to Hurricane Katrina, and his poll numbers suffered as a result. Obama was praised for his proactive response to Hurricane Sandy, and there’s some evidence he was rewarded for it in the 2012 election.

A much more detailed analysis of presidential performance tells the same story. John Gasper and Andrew Reeves show that while both presidents and governors are punished for natural disasters, they are rewarded for proactive responses to them.

In keeping with those findings, Trump has vigorously defended his performance amid mounting criticism. The president tweeted that the White House has a “perfectly coordinated and fine tuned plan” for confronting the outbreak and credited his response for the limited number of cases in the United States. He even erroneously blamed Obama for the lack of coronavirus tests for Americans.

But the president’s position is becoming increasingly untenable as the virus spreads across the country. Indeed, public disapproval of how Trump is handling the coronavirus outbreak spiked sharply from February to March in weekly YouGov-Economist polls.

The figure above shows that disapproval of Trump’s coronavirus performance increased from 30 percent in February to 47 percent March. A plurality of Americans, 36 percent, now strongly disapproves of how Trump is handling the outbreak.

This growing perception that the president is doing a poor job of responding to the public health crisis poses serious political risks. Presidential performance on salient issues tends to become a stronger predictor of Americans’ vote choices for president over the course of the election year.

Democrats have a big advantage on health care

Some political science research argues that the main goal of presidential campaigns is to emphasize issues where they have advantages and their opponents don’t. The increased attention to health care from the coronavirus outbreak should therefore help the Democrats — because Americans trust Democrats a lot more than Republicans to handle the issue.

Half of registered voters surveyed in a November 2018 Washington Post-ABC poll said they trusted Democrats to do a better job of handling health care, compared with just 34 percent who thought Republicans would do a better job. The Democratic Party had an equally large issue advantage on health care in 2019 polls conducted by the Associated Press and the Kaiser Family Foundation.

The coronavirus could hurt the president, then, by making health care a defining issue in the 2020 campaign. However, that would happen only if the virus is not contained come fall.

Although the economic effects of the outbreak are likely to last longer, the other political risks discussed will depend in large part on whether the virus is still spreading during the fall campaign. If the coronavirus is not contained by Election Day, it probably will hurt the president at the polls.