First of all, before you complain, no, it is not too early to talk about the 2020 election. It is not. The RealClearPolitics polling average for the Republican primaries in 2016 began in July 2013, with eventual winner Chris Christie holding a narrow lead over 2016 runners-up Marco Rubio and Rand Paul. No, Donald Trump wasn’t included in those polls. Why do you ask?

In other words, I’m granting you that 2020 polling from three-plus years in advance is not necessarily going to tell us who will win. That said, however, it can tell us something about what’s going on today.

For example. Fox News released a poll on Wednesday asking an interesting variant on the “if the election were today” question. If the 2020 election were today, Fox asked, would you support Donald Trump for reelection, or would you vote for someone else?

You can see how this question might go either way. Trump’s not terribly popular, so you have to figure that more people would vote against him. But, then, a recent Post-ABC News poll found a great deal of loyalty among Trump fans, with 96 percent saying they’d vote for him again today in a rematch of the 2016 contest. Given the drop-off among Hillary Clinton supporters in that poll, Trump might even eke out a popular vote win if the numbers held in this imaginary re-do.

Those who made the former guess were correct. In the Fox News poll, 36 percent of respondents say they would vote for Trump in 2020 if that election were today, with a fifth of the population saying they would definitely do so. By contrast, nearly half of Americans say they would definitely vote for someone else.

In total, 55 percent of respondents said they would definitely or probably vote against him. That includes 96 percent of Clinton voters, 94 percent of Democrats and 49 percent of independents. In fact, even 7 percent of Trump voters said they would probably vote against him in 2020.

There are a number of ways in which that figure isn’t necessarily at odds with the Post-ABC poll. For example, the margin of error among Trump voters in the Fox poll is 4.5 percent, which suggests that the group which might bail on Trump could overlap with that 4 percent that wouldn’t vote for him again in a rematch of the 2016 race.

But there’s also a core tenet of political polling that is always worth bearing in mind: An anonymous, theoretical candidate is almost always preferable to a real one. When Gary Johnson was pulling 10 percent of the vote in polling last summer, I used to note that, given a choice between someone people hate (Trump), someone people hate (Clinton) and someone people have never heard of, a lot of people will choose the person they’ve never heard of. (Then people started to hear of Johnson, and it went poorly.)

Given a choice between Trump and Anyone Else, the same rule applies. A lot of people will pick Anyone Else. That Anyone Else pulls more support from Trump fans than Hillary Clinton should not really be surprising.

That said, the Fox poll reinforces the long-term problem for Trump. He can’t count on his core base of support tripping past an unpopular opponent to an electoral college win again. He has got to do something to winnow down that 47 percent of the country that definitely plans to vote for Anyone Else. If he doesn’t, he will be as likely to win a second term as Chris Christie is to win the 2016 Republican nomination.