Commonly known by his initials, "AMLO", Lopez Obrador has proposed measures like a huge increase in infrastructure spending, but it's not clear how he can do that if he fulfills a promise not to raise taxes. Lopez Obrador has claimed victory in Mexico's presidential election, calling for reconciliation.
According to Mexico's National Election Institute (INE), Lopez Obrador was leading polls with 53% of the vote.
Former Mexico City mayor Obrador, who had already run for the presidency twice before, cast himself as an anti-establishment candidate prepared to crack down on corruption and to help the poor.
Jose Antonio Meade of the ruling Institutional Revolution was said to be in third.
According to exit polls, the sharp-tongued, silver-haired politician known as "AMLO" won by a large margin over his two main rivals, who both conceded defeat shortly after the polls closed - laying to rest concerns that a deeply divided country could face prolonged uncertainty over the victor.
Lopez Obrador is a twice-spurned populist whose supporters hope he will deliver on promises to clean up corruption, reign in spiraling violence and lift millions out of poverty.
Lopez Obrador's rivals argued he could set the country back decades and lead to disaster with an interventionist economic policy.
Amid widespread frustrations with the status quo, all of the candidates have tried to paint themselves as the agent of real change.
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The nearby boat then moved close to the burning vessel and attempted to rescue the injured passengers and crew. The explosion appeared to completely engulf the boat in flames as thick, black smoke pillowed into the sky.
"There is a lot of inequality, a lot of violence in this country", said Lopez Obrador voter Hugo Carlos, 73.
But in taking that stance for his own support base, AMLO might find a historic opportunity: building bridges with Mexico's southern neighbors, and perhaps also emergent powers such as China. His allies are warning even before Sunday's presidential vote that there better not be any amusing business.
The PRI, which dominated Mexican politics for almost the entire 20th century and recaptured the presidency in 2012, was set to suffer heavy losses not just for the presidency but in down-ballot races as well. In fact, in the eyes of many Mexicans, Mexico has been too respectful.
Most voting locations in Mexico closed at 6 pm, local time.
Ediane Da Costa Pereira is a Brazilian who became a naturalized citizen in Mexico and voted Sunday in Tijuana, across the border from San Diego.
Lopez Obrador struck a conciliatory tone in an acceptance speech Sunday night, saying he would pursue fiscal discipline and respect the independence of Mexico's central bank.
In an interview with the Televisa news network, Lopez Obrador did not provide specifics on what an "understanding" with the Trump administration might look like, except to emphasize the need for mutual respect and co-operation between the two neighbours. "We share common goals, strong people-to-people ties, and a mutually beneficial trading relationship that is the envy of the world - reflected in our joint effort to update the North American Free Trade Agreement for the 21st century", Trudeau said in a statement congratulating Lopez Obrador on his win.
Trump - who during his presidential campaign charged that some Mexican immigrants were "criminals" and "rapists" - early in his presidency ordered the building of a wall along the 3 200km US-Mexico border. What followed was a landmark energy reform by outgoing President Enrique Pena Nieto to reopen the oil and gas sector to foreign investors. Newspaper El Financiero's exit poll gave him 49 percent of the vote to 27 percent for Anaya and 18 percent for Meade. "We'll see what happens", Trump said. Mexico started separating Central American children from their parents long before the USA adopted the controversial policy.