The 64-year-old has not given specific details of how the "popular consultation" would be carried out.
The head of the National Regeneration Movement (MORENA) has previously suggested he could put a series of economic reforms - which include oil, education and telecoms overhauls pushed through Congress by Pena Nieto - to public referendums, but has given few details.
An official quick-count revealed that Lopez Obrador took the lead with 53-53.8% of votes, according to the electoral authority.
They're scheduled to end at 6 p.m.in each of Mexico's three summer time zones, meaning the last to close will come in the northwestern state of Baja California.
Obrador's coalition is also striving to win a congressional majority and six of the nine governorships on the ballot, Yahoo News reported. Its candidate, Jose Antonio Meade, has experience in several areas of government - including the treasury and foreign relations departments - and that convinced some voters like Roman Acosta, a doctor from the western city of Morelia. The winning candidate said he will make that proposal in a meeting Tuesday with current President Enrique Pena Nieto.
Trudeau later spoke with Lopez Obrador on Monday, wherein they discussed their mutual trade interests and their "shared priority of updating the North American Free Trade Agreement for the betterment of their peoples", said a readout of the conversation issued Monday. Those talks have been stalled over the Trump administration's demands for higher US content and a "sunset clause" in the 1994 trade agreement.
But on Sunday morning in Mexico City, many people were watching Spain and Russian Federation face off in the World Cup instead of election coverage. This is Lopez Obrador's third bid for the presidency and some see it as his best shot after 12 years of near-permanent campaigning.
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Andres Manuel Lopez Obrador is one of four candidates in the race to become the 58th president of Mexico.
U.S. Commerce Secretary Wilbur Ross told CNBC that Mexico "needs some sort of an arrangement" given its dependence on American consumers and businesses, having shipped $314 billion in goods to the United States past year.
Lopez Obrador also spoke of support for migrants and said the most forgotten and humble people of Mexico will be given preference in his government. He has also promised to increase spending on social programs while keeping government spending under control.
Polls had tipped a wide victory for Lopez Obrador, who many investors are expecting will govern from the center. Lopez Obrador's supporters began wild celebrations in Mexico City, cruising up and down the central Paseo de la Reforma boulevard honking horns to the tune of "Viva Mexico!" and waving Mexican flags from auto windows and moon roofs. Thousands poured into the Zócalo, the city's main square, to hear their former mayor speak to his supporters. Retired teacher Susana Zuniga beamed and said the country was experiencing a moment similar to the Mexican Revolution a century ago. "That is what brought us to this", she said.
Venezuelan President Nicolas Maduro has sent a tweet calling Lopez Obrador's presidential election victory "the triumph of truth over the lie".
People cast their vote during the presidential election on a polling station in Xochimilco, Mexico City on July 1, 2018. Mexico had a record 25,000 murders previous year, Yahoo News reported. Mario Ritter adapted it for VOA Learning English with additional material from AP.
In his words, "We are never going to disrespect the USA government, because we want them to respect us". Write to us in the Comments section, and visit our Facebook page.