Campaigning officially begins Friday for elections likely to produce Mexico's first woman president -- a watershed for a nation with a long tradition of macho culture.
Rival rallies were planned as the race heats up for the June 2 vote, including an opposition gathering after midnight in one of the country's most violent states.
Former Mexico City mayor Claudia Sheinbaum, a close ally of outgoing President Andres Manuel Lopez Obrador, known by his initials AMLO, is representing the ruling Morena party.
Public opinion surveys show the 61-year-old scientist by training enjoys a significant lead with 63 percent support, according to a poll of polls by the Oraculus research firm.
Her main rival Xochitl Galvez, the 61-year-old candidate for an opposition coalition, has 31 percent support, while Jorge Alvarez, 38, of the Citizens' Movement party is a distant third with just five percent, polls show.
"Sheinbaum is in a very strong position, with a significant lead in the polls over Galvez," analyst Michael Shifter of the Inter-American Dialogue think tank in Washington told AFP.
"Although nothing is impossible in politics, with just over three months to go before the election, it is highly unlikely that Galvez will be able to gain enough ground to make it a competitive race. AMLO is too popular, and the government and party machinery is too formidable," he added.
Sheinbaum is a staunch supporter and confidant of Lopez Obrador, a leftwing populist who enjoys an approval rating of nearly 70 percent according to Oraculus, but who is required by the constitution to leave office after one term.
The granddaughter of Bulgarian and Lithuanian Jewish migrants, Sheinbaum has vowed to continue Lopez Obrador's policy agenda.
She is due to address supporters on Friday afternoon in Mexico City's square, the heart of the city she governed from 2018 until last year when she stepped down to run for president.
Galvez, a 61-year-old outspoken businesswoman with Indigenous roots, opted to put the focus on the country's insecurity with a planned rally shortly after midnight in the city of Fresnillo in violence-wracked Zacatecas state.
She said that the choice of location was to send a "message of hope to all Mexicans that this long night of violence will end because we're going to confront the criminals."
It will be the first of several planned stops in cities considered by their residents to be among the most unsafe in Mexico, to highlight what Galvez says is the government's failure to tackle spiraling violence.
Nearly 450,000 people have been murdered across Mexico since the government deployed the military in the war on drugs in 2006, according to official figures.
Lopez Obrador angrily denied recent claims in US media that drug traffickers helped fund his first presidential campaign in 2006, and that US law enforcement officials spent years examining allegations that people close to him took millions of dollars from criminal gangs.
Shifter thinks the accusations "certainly raise important questions but will probably not get much traction with most Mexicans and will not cut into Sheinbaum's comfortable lead in the polls.
"On the contrary, AMLO could even get a boost by making the case that he is being persecuted by the foreign press," he added.
Galvez represents an opposition coalition made up of the Institutional Revolutionary Party -- which ruled the country for more than 70 years until 2000 -- the conservative National Action Party and the leftist Party of the Democratic Revolution.
But her background sets her apart from the traditional conservative opposition -- she wears Indigenous clothing, uses colloquial language peppered with swear words and is known for traveling around Mexico City by bicycle.
