The 'chin music' worked
In baseball, the pitcher often sends the batter a message — chin music, as they call it. It's an inside pitch that pushes the batter back a bit.
In trade talks, chin music is the threat of tariffs — I will make your country's goods and services a bit more expensive.
It looks as if Trump's "chin music" pitch got López-Obrador's attention, according to news reports:
In a news conference in the Gulf of Mexico port of Veracruz, President Andres Manuel Lopez Obrador said Mexico could be ready to step up measures to contain migration in order to reach a deal with the United States.
A Mexican delegation led by Foreign Minister Marcelo Ebrard will discuss the dispute with U.S. officials in Washington on Wednesday, and Lopez Obrador said he expected "good results" from the talks, and for a deal to emerge.
"The main thing is to inform about what we're already doing on the migration issue, and if it's necessary to reinforce these measures without violating human rights, we could be prepared to reach that deal," Lopez Obrador said.
My guess is that López-Obrador will play ball and do something to resolve the issue. First, the Mexican economy slowed up in the first quarter, as the aforementioned article notes. Second, the Mexican public is getting tired of the caravans, as we see in this recent article. My own unscientific survey confirms that people are ambivalent and starting to complain.
What happens next? We will see, but it looks as if Trump's chin music got López-Obrador's attention.