Believe it or not, we're now 100 days and 15 hours from the 2020 election. As we enter the final stretch of the campaign, presumptive Democratic nominee Joe Biden continues to hold an advantage over President Donald Trump in the polls.

A look at history reveals that while Biden's clearly the favorite, his victory is not assured in an unprecedented election.

1. This is the rare election not about the economy

A Fox News poll earlier this month revealed that 29% of voters said coronavirus/Covid-19 was the most important issue facing the country. That was nearly double the 15% who said the economy.

Going back over time, there have only been a select number of modern elections not about the economy. In each of those elections, the candidate trusted most on this non-economic issue went on to win.

Indeed, vote choice is currently strongly correlated with whether voters think Biden or Trump can better handle coronavirus.

The fact that coronavirus is playing such a big role in voters' perceptions of Biden, Trump and the presidential race means that for now Trump's in big trouble. But it also means that if the coronavirus picture changes for the better by November, Trump could come back.

2. That said, Trump's approval rating is really bad

Right now, Trump has approximately a 40% approval rating and a 55% disapproval rating. This makes for a net approval rating of -15 points.

Since 1940, no president has ever won another term in the White House with such a poor net approval rating at this point. The closest was Harry Truman in 1948, whose approval rating was nearly 10 points better at -6 points.

As a group, the presidents (Gerald Ford, Jimmy Carter and George H.W. Bush) who were not elected to a second term look eerily similar to Trump. Their average net approval rating stood at -13 points.

Trump's net approval rating isn't anywhere close to the average president who has earned another term, +23 points.

3. A Trump win is still within the margin of error

Biden is up by anywhere from eight points (including all polls) to 12 points (just live interview polls) in the national average, depending on how you compute it. That's a sizable edge.

If you look at the polling 100 days out from each election involving an incumbent since 1940, the average difference between the polls at this point and the result has been 10 points. If you look at the elections (seven) where we were not in-between conventions at this point, that difference drops to six points.

Trump would need an average to above average error to win the national vote. He would also need that error to go in his direction and not actually benefit Biden. That's unlikely to occur.

Still, he can take some hope from Truman in 1948, who was down by about the same in the national polls right now. Truman would go on to win by five points.

4. Biden's advantage in the electoral college is clear

If you were to average the polls in every state, Biden leads in states containing 352 electoral votes to Trump's 186. He's additionally within a point in Georgia (16 electoral votes) and Texas (38 electoral votes).

It's quite conceivable that Biden would win over 400 electoral votes, if the election were held today.

Perhaps as importantly, there is little sign that the electoral college will doom him like it doomed Hillary Clinton in 2016. His average lead in key states like Florida, Michigan, and Wisconsin look quite similar to his advantage nationally.

5. This election looks nothing like 2016

Speaking of the 2016 election, Biden's in a much better position than Clinton. Consider this fact: Clinton was hitting her apex in the national polls at this very moment. She had just wrapped up a successful Democratic National Convention, and she held an average 44% to 38% lead in two live interview polls completed 100 days from the election.

Biden's at 52% to Trump's 40% in the live interview national polls taken in July. That is, he's over 50%, unlike Clinton, and has basically double the lead Clinton was holding after her convention.

Biden continues to have a better favorable rating and is viewed as far more honest than Clinton.

Simply put, you'd much rather be Biden than Trump. But with some time to go, there's still time for a Trump comeback.