The total includes about 19,000 unaccompanied migrant children and 53,000 family members traveling together, the preliminary figures show. Single adults made up roughly 99,000 of the total.
The Biden administration is struggling to find housing for unaccompanied children who have been backed up in crowded border stations and processing centers for days.
It could also encourage Lopez Obrador to position himself as a champion of free speech, deflecting criticism that he uses his morning conferences to pillory adversaries.