Mexico’s president Andrés Manuel López Obrador is throwing his support behind President Joe Biden’s immigration reforms, but the country’s recent clamp down on DEA investigations has put the U.S.-Mexico relationship on security matters in what one expert called a “deep freeze.” Mexican President Andrés Manuel López Obrador stands during the commemoration of his second anniversary in office, at the National Palace in Mexico City, on December 1, 2020. (AP Photo / Marco Ugarte ) HOUSTON (CN) — Donald Trump’s departure offers the U.S. and Mexico a chance to reboot their diplomatic relations, yet American concerns about corruption in Mexico has emerged as a stumbling block to solidarity.