The backlash increased throughout the day as Pena Nieto stood by Trump in an address to the media where the candidate remained firm on a proposed border wall and played the role of statesman with such pearls as "Mexicans are fantastic!"
Trump didn't back down on his plans to build a wall at the US southern border. He poured forth an hourlong harangue against all things alien, highlighting the lurid crimes of a handful of illegal immigrants as if to define the character of millions.
Democratic vice presidential candidate Tim Kaine says Donald Trump "choked" by not demanding to Mexico's president that his country pay for a border wall.
Trump also said he's going to hold other countries accountable. The Trump campaign didn't immediately respond to a request for comment on the hat.
That was not a minor point, but rather a sore one.
Trump, the GOP presidential nominee, also appointed a new campaign manager and chief executive last month amid sliding poll numbers. "And they're great people and great leaders but they're going to pay for the wall", said Trump.
Trump has previously called Mexicans "rapists", suggested that a federal judge was biased against him due to his Mexican heritage, and put his promised wall along the US-Mexico border at the center of his campaign. Rest assured, they seemed to say, Mexico will come around.
Even as he beat a retreat from his earlier pledge to deport all illegal immigrants from the country, Trump's aggressive tone in Phoenix marked a shift from earlier in the day. "My first hour in office, those people are gone", he said.
Within hours, Trump wiped it all away. But the critical issue of Trump's speech was not violent criminals. One imagined Kellyanne Conway, the pollster-cum-campaign manager, arguing for the quickie trip to Mexico and the confab with Peña Nieto.
"I was very clear - in private and in public - in stressing that in Mexico we feel offended and hurt by his pronouncements about Mexicans", Pena Nieto wrote in a piece in the newspaper El Universal on Thursday entitled "Why did I meet Donald Trump?".
If the visit serves to moderate Trump's rhetoric, then that might provide an explanation for Pena Nieto's decision to see him in the first place, said Selee. Because two weeks of adverse publicity about the Clinton Foundation and its donors and about newly discovered emails at the State Department have helped erode Hillary Clinton's already weak standing with voters. He called Trump's speech the outline of "a coherent and workable strategy".
For as soon as that moderating narrative got airborne, Trump's speech in Phoenix took off after it with the speed and fury of an anti-aircraft missile.
Trump advisers were jubilant after the visit, as was the candidate. On "CBS This Morning", Kaine said Trump "didn't have the guts to look the Mexican president in the eye" and demand that Mexico pay for the wall.
Trump is trailing Clinton in surveys and several of Trump's major Latino supporters said they are considering dropping their backing following his speech, Politico reported.