Donald Trump's electoral challenge isn't really about 270, the number of electoral votes he needs in order to win. It's about 26 -- the number of states he needs. That's two more than Mitt Romney won in 2012, and it's the bare minimum Trump needs if he doesn't lose in any place that Romney prevailed. Which states he wins is important, too -- but less so right at this moment. Why? Because as The Post's new 50-state poll with SurveyMonkey reveals, Trump's in very bad position relative to where Romney ended up.

The simplest way to view this is by looking at the results from our poll in each state compared to how Romney did four years ago. This is margins; anything to the left of the center vertical line shows Hillary Clinton leading in a state. Anything to the right is a Trump lead. But the diagonal line is what we're looking at here. All those red dots above the diagonal line show Trump doing worse in states that Romney won.

What's worse is when we overlay the number of electoral votes in each state. Florida, Ohio and Texas (!) are all in the middle, but only in Ohio is Trump outperforming Romney. There are a lot of states with a lot of electoral votes that are firmly in Clinton's column.

(Notice Utah on that chart. We'll come back to it.)

If we compare how Romney did versus John McCain in 2008, the situation is flipped. In nearly every state that Romney won, he did better than McCain had. The dots in this case are below the line.

To explain the differences, let's pull out three groups of states: The 12 states that favored Clinton the most in our poll, the 12 friendliest to Trump and the 12 states where the margin was under 5 points between the two.

Among nonwhite voters, the margins are pretty consistent. What makes the difference between those three groups (in addition to the number of nonwhite voters in the states, of course) is where the white voters land. States friendliest to Clinton have white voters on-board. States friendliest to Trump, he's winning by wide margins on average.

One difference in the white vote is by educational and gender groups. White men without college degrees consistently prefer Trump, but by slightly less in states that are friendliest to Clinton. White women with degrees are much more likely to back Clinton in states she leads by a wide margin.

There's another interesting difference. In the 12 states where Clinton leads by the most, the percentage of support she gets from Democrats is far larger than the percentage of support Trump gets from Republicans. That narrows as the states become friendlier to Trump, but even in the 12 states where he does best, Republicans prefer him only slightly more than Democrats prefer Clinton, on average.

This brings us back to the question of how Trump is doing compared to Romney. If we plot how he fares with Republicans versus Romney's final results in 2012 (an idea pilfered from the University of Wisconsin's Barry Burden), you can see that Trump gets less support from Republicans in nearly every state than Romney did. Exceptions are highlighted -- as are places where Trump is doing far worse, like Utah. We've talked about Utah in the past; we'll just say for now that its soft support for Trump is not only a function of the state being a second home to Romney.

Contrast that with Clinton. She's faring worse with Democrats than President Obama did four years ago in most states (in part because both her and Trump's numbers are a bit lower before undecided voters commit to a candidate). But where she does better or worse makes sense: Better in Arkansas and worse in Indiana (thanks to Mike Pence, no doubt), worse in Hawaii and Vermont (the latter thanks to Bernie Sanders).

Clinton is doing better than Obama with Democrats in eight states. Trump is outperforming Romney with Republicans in two.

Trump's problem is, in part, that he seems to be disliked more by moderate Republicans and Republicans with degrees than he is liked by white men without degrees. We made a tool to illustrate that clearly over the weekend, but the state-by-state poll reinforces the main point. Trump is leading with the latter group (in The Post's August national poll) by 11 more points than Romney led in 2012. With women with degrees, he's doing 25 points worse.

Donald Trump needs, simply enough, to do better than Mitt Romney in order to win. At this point, he isn't.