If Trump does go on to lose in November, he doesn’t just need to worry about losing to Biden. Trump needs to worry about the fact that the history books are probably going to put him down as a below average president, if not one of the worst.
The average ranking for presidents who win a second term is 14th. That’s well above average given we’ve had 44 presidents. None ranked lower than 32nd (George W. Bush). The best was the top spot overall (Washington).
The average for presidents who did not win a second term is 30th. That’s well below average. None of the presidents who didn’t have a second term ranked higher than 13th (John Kennedy, who was assassinated). The worst was last overall (Buchanan).
Just on this basis alone, you’d think that Trump would probably go down as below average if he lost in November. We wouldn’t know quite where he’d land, but it’d be a pretty good bet that he wouldn’t finish in the top half.
I’d bet Trump would dip even lower given where the historians already have him. The average of the APSA and Siena polls put Trump at 43rd, which ties him for last with Buchanan.
Since 1948, the final historian rankings of a president during their time in office (or the first after they leave office) has differed from their current ranking by just four spots. The median difference has been a mere two spots. The presidents who tend to improve the most (such as Dwight Eisenhower) are ones who get that second term.
Now, there is obviously some chance Trump could be ranked higher than at the end of 2018. I tend to doubt it, though, because his standing among the public is not any better now than it was then.
All told, historians at the end of his first term are likely going to view Trump quite negatively. His only real chance of seeing improvement is to earn that second term, which seems to be something that is becoming less likely by the day.