GUADALAJARA, Mexico — Mexico’s new president, Andres Manuel Lopez Obrador, rose to power on the promise that he would tackle the country’s rampant corruption and violence.

That will have to wait, as he faces a more urgent matter: the migrant crisis at the U.S.-Mexico border.

Thousands of migrants have arrived in the northern city of Tijuana in recent weeks, having trekked through Mexico as part of the caravans from Central America that began forming in October. Most of them have...

Continue Reading Trump has already created a crisis for Mexico’s new president