Can President Donald Trump do it again? Will he be able to convince enough undecided or uncommitted voters to give him another four years in office?

At the moment the short answer is “No”.

Looking just at the 2020 polls, an election observer could be forgiven for thinking that former Vice President Joe Biden has an easy path to unseating Trump. Yet few prognosticators are proclaiming an impending Biden victory. Perhaps this is because, despite a similar deficit in the summer of 2016, then-candidate Trump surprised everyone with an election night victory over his Democratic rival Hillary Clinton.

A big part of that 2016 story is late-deciding voters decisively breaking towards Trump, potentially handing him victory and several swing states. One post-election analysis (APPOR 2016 Post-Election Report) found that Trump gained an average of 1% nationally and 3% in four swing states due to outperforming Clinton among the roughly one-in-eight voters making their decision in the week before Election Day.


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This year, undecided voters are more likely to be female, less likely to have a college degree, more likely to be younger, and are more likely to be a person of color.

... Democrats are much likelier than Republicans to say they will vote by mail — which makes sense given that Democrats also tend to be more supportive of mail voting. (By contrast, the Republican standard bearer, President Trump, has repeatedly and inaccurately assailed mail voting as ripe for fraud.)

According to a recent NBC News/Wall Street Journal poll, 30 percent of registered voters said they planned to vote by mail, and 43 percent said they planned to vote in person on Election Day. But among Trump supporters, only 11 percent said they planned to vote by mail, and 66 percent said they planned to vote in person on Election Day. Among Joe Biden backers, 47 percent said they planned to vote by mail, while only 26 percent said they planned to vote in person on Election Day. (The share who said they would vote early in person was consistently 20-21 percent among all three groups: Trump supporters, Biden supporters and voters overall.)

If this holds, it would mean votes cast on Election Day would skew heavily toward Trump, and votes cast by mail would skew heavily toward Biden. This has serious implications for … well, democracy. First, Trump could argue the mail ballots (which, remember, could account for most of Biden’s votes) were fraudulent and thus should not be counted. Although it’s unlikely they’d actually be thrown out, this would damage the credibility of the election in the eyes of many Trump supporters. Second, it could mean the first votes counted on election night will be disproportionately good for Trump, who might claim victory based on incomplete returns. It might not be until days later, after a good chunk of the Democratic-leaning mail vote is counted, that Biden pulls ahead.

Even with limited data, the implications are considerable. NPR found that tens of thousands of ballots have been rejected in key battleground states, where the outcome in November — for the presidency, Congress and other elected positions — could be determined by a relatively small number of votes.

For example, President Trump won Wisconsin in 2016 by almost 23,000 votes. More than 23,000 absentee ballots were rejected in the state's presidential primary in April. More than 37,000 primary ballots were also rejected in June in Pennsylvania, a state Trump won by just over 44,000 votes.

The numbers are also significant because of large partisan differences in how Americans plan to vote this fall. Democrats have expressed more interest than Republicans in voting by mail — 47% to 28% in the Democracy Fund/UCLA survey. Forty-eight percent of those who intend to vote for Joe Biden say they will use mail-in ballots, compared with 23% of Trump supporters.