Two Mexican opposition candidates on Sunday vowed to take a tougher line against US President Donald Trump's border wall, at events where they were selected by their parties to seek the presidency in a July 1 election.
Andres Manuel Lopez Obrador, 64, of the leftist Morena party holds a double-digit lead in recent polls although right-left coalition leader Ricardo Anaya has recently gained traction.
Former finance minister Jose Antonio Meade, 48, nominated on Sunday by the ruling Institutional Revolutionary Party (PRI), trails behind Lopez Obrador by as much as 20 points.
Lopez Obrador told several hundred Morena supporters gathered at a Mexico City hotel that Trump's plan for a U.S.-Mexico border wall is unnecessary and bound to leave problems unresolved.
"If he insists on building the wall, we're going to turn to the United Nations to defend the rights of Mexicans,"he said."I'm conscious of my historic responsibility."
The former Mexico City mayor who has run twice for the presidency also promised to combat inequality, crime and corruption, key election issues for all of Mexico's main political parties.
Anaya echoed Lopez Obrador's opposition to a US-Mexico border wall, refusing to pay for its construction and saying he would be tougher than the PRI to defend Mexico's independence.
"Mexico will never again be treated like a doormat for the United States, as it's been in this government,"said Anaya, who is backed by the center-right National Action Party (PAN) and the center-left Party of the Democratic Revolution (PRD).
The youngest of the three candidates, Anaya, 38, said in a CEO-style presentation at an auditorium in the capital that he would fight public corruption, raise the minimum wage and improve education to support an economy based on"knowledge"rather than"manufacturing."
Meade pledged in his nomination acceptance speech at a Mexico City stadium to crack down on crime and impunity, issues that have dogged the current administration and hurt the PRI's credibility.
With six weeks to go before campaigning begins for the July 1 vote, Meade's campaign says early polls have traditionally been unreliable indicators of final results in Mexico.
"If this trend continues, the race will become more competitive between the two front runners,"political risk analysts at Eurasia Group said in a note on Friday.