Garbage and a sign is seen after President Trump spoke at a "Keep America Great Rally" in New Hampshire. (Jabin Botsford/The Washington Post)

President Trump fails to crack 40 percent in any matchup with a potential 2020 opponent in a new Fox News poll. And that may not be the worst of it for him.

The new Fox poll is arguably Trump’s worst of the early polls testing potential general-election matchups. He trails Joe Biden by 12 percentage points (50 percent to 38 percent), Sen. Bernie Sanders (Vt.) by nine points (48 to 39), Sen. Elizabeth Warren (Mass.) by seven (46 to 39) and Sen. Kamala D. Harris (Calif.) by six (45 to 39). That’s tied for his biggest deficit to date against Warren, according to RealClearPolitics, and it’s close to his biggest deficits against the others, too.

It’s just one poll of course, and even high-quality polls have margins of error. It’s possible Trump’s support percentage is really in the 40s, just like in most other polls.

But if you drill down, there are a couple other problematic pieces of this poll for Trump.

The first is his vote share versus his approval rating. There has been plenty of talk about Trump’s consistently low approval rating and how it sets him up for reelection. But in this poll, he doesn’t even completely lock down that vote. While he gets 38 to 39 percent in all four matchups, his approval rating is actually 43 percent. That means roughly 4 percent of registered voters say they approve of Trump but they’re not ready to vote for him.

And as Josh Jordan noted, this isn’t the first poll to show that. I looked back on three other high-quality national polls and found a drop-off in all three — albeit not as big as in Fox’s poll.

Poll Approval Avg. vote share
Fox News 43% 39%
NBC/WSJ 45% 43%
WaPo/ABC 47% 46%
Quinnipiac 42% 41.5%

Reelection bids are generally viewed as referendums on the incumbent in which, in a close race, you’d expect the president to at least get the percentage of voters who approve of him. For Trump, it appears there is a small percentage of people who like the job he’s done but for whatever reason — concern about his tendency to fly off the handle, perhaps, or the fact that they also like the Democrats — aren’t yet on board with his reelection. It’s one thing to run for reelection with a low approval rating; it’s another to not even be able to count on that level of support.

An alternative reading, of course, is that these voters are ripe for Trump to bring back into the fold and increase his vote share as the race moves forward. But even then, he’s not in great shape.

The second problematic number comes from Fox News’s write-up of its poll:

Voters who have a negative view of both Biden and Trump back Biden by a 43-10 percent margin in the head-to-head matchup, although many would vote for someone else (27 percent), wouldn’t vote (12 percent) or are undecided (8 percent).

This is an admittedly small subsample (just 108 people), with a very large margin of error. But even accounting for that, this is ominous for Trump. That’s because these voters — those who disliked both him and Clinton — made the difference for him in 2016. As Philip Bump wrote last month:

Nationally, Trump had a 17-point edge with those voters, according to exit polls. In the three states that handed him the presidency — Michigan, Pennsylvania and Wisconsin — he won those voters by 21, 25 and 37 points, respectively. In each state, those voters made up about a fifth of the electorate.

It was one-fifth of the electorate because only about 40 percent of voters liked both Trump and Clinton. It’s a smaller universe today, because Trump’s image is slightly better and Biden’s is significantly better than Clinton’s. But it’s also true that this universe of voters probably comes more from the right side of the electorate, given Biden’s superior image rating. And yet Trump barely gets any support here.

For now, let’s set aside the numbers in the head-to-head matchups. The fact is that Trump can win reelection with an approval rating in the low-to-mid 40s, which is where it’s been throughout his presidency. But he can’t do it if he’s not locking down basically everyone who approves of him and is getting beaten among those who dislike both him and his Democratic opponent. If those findings are accurate, then focusing on his low approval rating might actually oversell his reelection chances.