Mexican President Enrique Peña Nieto gives a speech in January. (Omar Torres/AFP/Getty Images)

It is barely worth pointing out that Donald Trump's surprise visit to Mexico on Wednesday won't do President Enrique Peña Nieto much good. Peña Nieto is deeply unpopular in his home country, with a quarterly survey from the newspaper Reforma putting his favorability at 23 percent — a figure so low that it makes Trump himself, at 35 percent, seem positively embraced.

That 35 percent is in the United States, of course. In Mexico, Trump's a lot less popular. A June survey showed Trump at 75 percent unfavorability in the country — compared with Hillary Clinton's 6 percent. When Ipsos asked people around the world in June who they'd pick in the American presidential contest, no country saw a wider gap than Mexico. Mexico preferred Clinton to Trump by an 88-to-1 margin — an 87-point spread. (The only countries that preferred Trump were China and Russia.) The next-closest countries were Belgium and Sweden, where Clinton was preferred by 66 points. There's a correlation between Trump's poll numbers and the Mexican economy: When he does better, the value of the peso has dropped.

Republican presidential nominee Donald Trump is slated to meet with Mexican President Enrique Peña Nieto as he tries to clarify his past comments about Mexico and immigration. (Jenny Starrs/The Washington Post)

Less than 12 hours after the news of Trump's visit broke, other Mexican politicians had already weighed in to oppose welcoming Trump to the country. Politico collected some examples. "We are threatened with war and walls, but we open the National Palace," the president of the Mexican Senate wrote, adding that the invitation approved of Trump's "proposal of demagogy and hate." A former diplomat tweeted, "I feel embarrassed as a Mexican thanks to my president." On CNN on Wednesday morning, former president Vicente Fox (who has been outspoken about Trump) disparaged Peña Nieto's decision.

This response is not surprising. From the first moments of his candidacy, Trump railed against Mexico. Even before that, he complained about Mexico on Twitter, in part because he won a lawsuit in the country but hasn't been able to collect.

From our standpoint, though, the bigger question is how this benefits Trump.

In the past, Peña Nieto has criticized Trump and his proposals. In March, Peña Nieto compared Trump to Adolf Hitler and Benito Mussolini, saying that Trump's "strident" rhetoric was of a piece with the arguments those leaders used to gain power. Peña Nieto has also flatly rejected Trump's signature policy proposal, to build a wall on the border and have Mexico pay for it. Not going to happen, Peña Nieto said to Fareed Zakaria of The Washington Post and CNN: "There is no way that Mexico can pay [for] a wall like that."

After Trump and Peña Nieto meet, that will be the first question that's asked of Trump. Did Peña Nieto agree to pay for the wall? (Unless, of course, Trump's arrival is met with the sort of demonstrations that his appearances have earned in the past in San Jose and San Diego.) Peña Nieto — unpopular! — has a clear political incentive to embarrass Trump on the issue, a sort of I-invited-him-here-to-boss-him-around sort of thing. It's perhaps Peña Nieto's only possible positive political outcome. But even if things progress quietly, it forces the issue: Trump says he'll make Mexico pay, and Mexico says it won't. Now what? Trump has never been able to answer that question.

Update: Sure enough.

(One deeply optimistic Trump supporter, former congressman Joe Walsh, figures that Trump obtaining a promise to pay for the wall would be "game, set, match," which is true. It is also true that if Peña Nieto gives Trump proof that Clinton was a space alien intent on destroying the globe that it would benefit Trump. Neither is likely to happen.)

What does Trump get out of it? We assume that Peña Nieto will pose for photos with the visiting dignitary (though that seems like a political miscalculation for him). Trump-as-statesman is a new one, and it will be interesting to see how it's handled. That photo itself encapsulates a lot of the risk-reward calculus for Trump: At best he gets a dull picture of himself standing next to a person with whom most Americans aren't familiar; at worst, he gets an awkward picture posing in front of the Mexican flag — something that some part of his base probably won't be thrilled about.

The trip will, at best, show that Trump can go to a foreign country and meet with leaders without incident, a fairly low item on the presidential checklist. (A subject for another time: Do voters actually care about a grip-and-greet?) At worst? Who knows.

The move feels a bit like John McCain's decision in September 2008 to suspend his campaign to deal with the economy. It felt gimmicky and didn't do much — and reinforced that McCain was in the sort of political position that necessitated gimmicks that might not do much. Barring a Joe-Walsh-esque miracle, Trump's trip to Mexico instills a lot of risk with the potential upside for Trump being that he proved he can do something fairly simple without incident. For Peña Nieto, the potential upside is that he can score points off an unpopular visitor; the downside is that he is seen as embracing someone his constituents vehemently dislike.

Given how low the reward is for Trump and how high the possibility that something might go wrong, there’s a decent chance that the politician for whom Trump’s trip is beneficial is his opponent.