Two Mexican presidential candidates have taken aim at President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE's plan to build a wall along the U.S.-Mexican border.

“If he insists on building the wall, we’re going to turn to the United Nations to defend the rights of Mexicans,” leftist presidential candidate and former Mexico City mayor Andrés Manuel López Obrador told hundreds of supporters, according to Reuters.

“I‘m conscious of my historic responsibility," he continued.

Right-left coalition leader Ricardo Anaya has vowed to defend Mexico's independence from the U.S. on the issue of the border wall.

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“Mexico will never again be treated like a doormat for the United States, as it’s been in this government,” Anaya said.

Reuters reports López Obrador as having a double-digit lead in the polls, however, Anaya's support has increased among Mexican voters.

Former finance minister José Antonio Meade is also running.

Mexico's presidential election will take place on July 1.

Trump campaigned on the promise of building a border wall along the southern U.S. border, and that Mexico will pay for the barrier.

The president has requested more than $23 billion for border security and immigration enforcement — including funds for a wall along the U.S.-Mexico border in his proposed 2019 budget.

Trump has also said that a renegotiation of the North American Free Trade Agreement could yield the money to pay for his long-promised wall along the U.S.-Mexico border.