Andrés Manuel López Obrador has been elected to the presidency in Mexico. He captured more than half of the vote Sunday and his election represents a shakeup in the country.

News analyst Charlie Sennott explained that López Obrador was elected as the country's first leftist president, winning the largest marginof the vote since the beginning of Mexico’s democracy.

“A real firebrand lefty has been elected in Mexico, and it's sort of a toppling of the traditional parties, particularly the P.R.I., the very famous big political party in Mexico that’s ruled forever,” said Sennott on Boston Public Radio Monday.

The P.R.I., or President Enrique Peña Nieto’s Institutional Revolutionary Party, and the National Action Party, or P.A.N., formerly led by Vicente Fox, have been the two dominant parties in Mexican politics. But with López Obrador’s victory, the country is rejecting the establishment and choosing a progressive party, the National Regeneration Movement.

“[Mexican citizens] always elected these technocrats who were pro-American in trade issues, and we always had these kind of warm relations. You’d always see this thing happening across the border with trade,” Sennott said. “This guy's different.”

Sennott said López Obrador campaigned against Donald Trump and is likely going to push back against expectations of “warm and fuzzy” trade relations.

“[He] campaigned very hard against the idea of getting rid of NAFTA and is really going to go hard in attacking Trump’s rhetoric,” Sennott said. “There will be heat coming from the South with this guy.”

Charlie Sennott is a news analyst at WGBH, where he also heads up The GroundTruth Project.