MEXICO CITY (Reuters, Washington Post, AFP, NYTimes) - Andrés Manuel López Obrador, who rallied voters with his battle cry against corruption and promises to the poor, won a resounding victory on Sunday (July 1) night in Mexico's presidential election, after the concession of his two top rivals.

The victory makes him the first leftist president since Mexico began its transition to democracy more than 30 years ago.

López Obrador triumphed with a party that didn't exist at the time of the last election, against opponents from two parties that have ruled Mexico for nearly a century.

The 64-year-old former Mexico City mayor promises to bring his humble lifestyle and distaste for luxury to the top of a political establishment famous for self-enrichment.

The results represent a resounding defeat for outgoing President Enrique Pena Nieto's ruling centrist Institutional Revolutionary Party (PRI), which has ruled Mexico for all but 12 of the last 89 years.

"There is so much wrong. I think some people voted for López Obrador, but the majority voted for a change that we need," said Fernando Torres, a 23-year-old publicity agent who was walking on Paseo de la Reforma, a major downtown boulevard.

López Obrador's victory represents an emphatic rejection of the traditional politicians whom he regularly calls the "mafia of power".

In recent decades, Mexico has been led by technocrats and pro-American politicians, while López Obrador's role models are Mexican independence and revolutionary leaders who stood up to more powerful foreign countries.

US President Donald Trump looms in the background of this vote. He has not been a wedge issue in the election - as all candidates have opposed his policies and anti-Mexican rhetoric - but the new Mexican president will have to manage cross-border relations that are unusually fraught.

The runner-up in the 2006 and 2012 presidential elections, Lopez Obrador pitched himself as the only one capable of cleaning up the government after years of poor economic growth and rampant gang violence eroded faith in the political class.

Seeking support from economic nationalists, leftist liberals and social conservatives, Lopez Obrador has been vague on policy details.

But he vows to reduce inequality, improve pay and welfare spending and run a tight budget.

López Obrador only has one prior electoral victory. In 2000, he became mayor of Mexico City, where he boosted social spending for single mothers, the handicapped and the elderly. Major projects, such as an elevated highway through the city, and the revitalization of downtown neighbourhoods, also boosted his popularity.

In building his third candidacy for the presidency, he cobbled together an odd group of allies, some with contradictory visions. There are leftists, unions, far-right conservatives and endorsements from the Catholic Church. How he will manage these competing interests remains to be seen.

López Obrador will inherit an economy that has seen only modest growth over the past few decades, and one of his biggest challenges will be to convince foreign investors that Mexico will remain open for business.

If he fails to convince the markets that he is committed to continuity, or makes abrupt changes to the current economic policy, the country could find itself struggling to achieve even the modest growth of prior administrations.

There is some evidence that López Obrador knows what is at stake. Though political rivals have painted him as a radical on par with Hugo Chavez, the former socialist leader in Venezuela, Mexico's president-elect has vowed not to raise the national debt and to maintain close relations with the United States.

The campaign season has been marked by brutal violence, with more than 140 candidates and campaign staff assassinated across the country since September, according to the consulting firm Etellekt. That makes these by far the most violent elections in Mexican history.

The victims included 48 candidates running for office - 28 of whom were killed during the primary campaigns and 20 during the general election campaign.

Most of the murders have been of local politicians, the most frequent targets for Mexico's powerful drug cartels.