Newly elected Andrés Manuel López Obrador has become the first leftist president of Mexico since the end of one-party rule in 2000. López Obrador said he would pursue friend and foe alike in a crackdown on corruption after voters handed him a strong mandate for a government with a landslide election victory Sunday.
López Obrador, won between 53 and 53.8 percent of votes, according to a quick count by the electoral authority, more than double the total for his nearest rival.
That would be the most significant share of the vote since the early 1980s and would give López Obrador a platform both to address Mexico's internal problems and face external challenges like the threat of a trade war with the United States.
Going into Monday it was unclear whether López Obrador had done enough to secure the first outright majority in Congress in over 20 years, with pollsters' early estimates suggesting he was close in the lower house but farther away in the Senate.
Speaking to reporters after his win, López Obrador identified corruption as the "principal cause" of inequality and the criminal violence that has bedeviled Mexico for years and said he would spare no one in his commitment to root it out.
"Whoever it is will be punished, I include comrades, officials, friends and family members," the 64-year-old said. "A good judge begins at home."
The election was a crushing defeat for the ruling centrist Institutional Revolutionary Party, or PRI, which governed Mexico from 1929-2000 continually and again from 2012.
Public anger over corruption scandals, which have shattered the PRI's credibility, was a defining feature of the campaign, alongside national discontent over soaring levels of violence and years of lackluster economic growth.
López Obrador, a former Mexico City mayor, was greeted with rapturous cheers by supporters in the capital's Zocalo central square around midnight, while friends celebrated in his tiny hometown of Tepetitan, in the impoverished southern state of Tabasco.
The victory was a justification for López Obrador, who was written off by many critics after narrowly failing to capture the presidency at his first bid in 2006.
Andrew Selee, president of the Migration Policy Institute in Washington, sees AMLO as a change from past Mexican leaders who were "obsessed" about being on good terms with the United States
"It means that the US can't take Mexico for granted anymore," he said. "López Obrador will be pragmatic ... but he's not going to bend over backwards to have a good relationship."
For his part, AMLO has vowed to respect the existing Mexican team renegotiating the North American Free Trade Agreement (NAFTA) with the United States and Canada.
"We are going to accompany the current government in this negotiation, we are going to be very respectful, and we are going to support the signing of the agreement," he told Milenio TV in an telephone interview, saying the aim was a deal on the North Atlantic Free Trade Agreement that was good for Mexico.
He also said he would pursue a frank dialogue but friendly relations with the United States. Lopez Obrador, who will take office in December, said he would discuss NAFTA with President Enrique Pena Nieto in their first meeting after the election, set for Tuesday.
U.S. President Donald Trump has been openly antagonistic to Mexico over trade and migration since his 2016 presidential campaign. The current NAFTA talks began last year after Trump called for the agreement to be renegotiated to serve U.S. interests better.
Although Trump congratulated Lopez Obrador in a Twitter message on Sunday night, a White House aide then reiterated one of the U.S. leader's most controversial campaign promises.
"In the case of Mexico, obviously we share a border with them (and) this president has made very clear about building that wall and having Mexico pay for it," Kellyanne Conway said on Fox News.
Mexican politicians across the political spectrum have long said that Mexico will not pay for Trump's proposed wall along the southern U.S. border, which he has said is needed to keep out both illegal immigrants and narcotics.
Lopez Obrador has said he wants to make Mexico more economically independent of the United States.
At the same time, he also hopes to persuade Trump to help develop Mexico and Central America to contain illegal migration.