Leftist Andres Manuel Lopez Obrador won Sunday’s presidential election by a landslide, ushering in a new era in Mexican politics that could have profound implications for the country’s domestic and international policies — including its relationship with the United States.

Lopez Obrador’s projected margin of victory was 31 percentage points — the largest in Mexico’s recent electoral history. His opponents conceded before any actual results were released, based on exit polls showing the firebrand populist’s commanding lead.