Shortly before virtual talks with US Vice President Kamala Harris on migration and trade, Mexican President Lopez Obrador sent a diplomatic note accusing the US of violating his country's sovereignty.
Biden has assigned Harris with leading efforts to cut immigration from Mexico, Guatemala, Honduras and El Salvador
US Vice President Kamala Harris held a virtual meeting with Mexican President Andres Manuel Lopez Obrador on Friday to discuss immigration policies. It was their second meeting in a month.
During the meeting, Harris and Lopez Obrador pledged to cooperate on resolving the roots of illegal migration into the US.
Harris said the US and Mexico must combat violence and corruption together, to help cut back migration from Central America.
"Most people don't want to leave home and when they do it is often because they are fleeing some harm or they are forced to leave because there are no opportunities," she said.
The two countries said they should work together on helping "Northern Triangle" countries — El Salvador, Guatemala and Honduras — improve conditions and persuade migrants to stay home.
"It is in our countries' mutual interest to provide immediate relief to the Northern Triangle and to address the root causes of migration," Harris said.
Lopez Obrador referred to the long-running issues of US-Mexican tensions over migration and said "we need to understand one another and avoid fighting."
"We are in agreement when it comes to the policies that you are undertaking when it comes to migration and we will help. That is what I can say as of now. You can count on us," he added.
The meeting comes at a time the Biden administration grapples with a surge in people crossing into the US at the southern border.
In March, President Joe Biden tasked Harris with leading diplomatic efforts to decrease immigration from Mexico and Central America.
Biden raised the US's annual refugee cap on Monday to 62,500. It followed pressure from the Democratic party and refugee agencies after initially sticking by the historically-low Trump-era figure of 15,000.
Shortly before the scheduled call with Harris, Lopez Obrador sent a diplomatic note asking Washington to explain funding for Mexicans Against Corruption and Impunity, a group critical of the Mexican government.
"It's promoting a form of coup," Lopez Obrador said, adding that the funding, which includes money from USAID, undermines Mexico's government and sovereignty.
"It is an interventionist act that violated our sovereignty… That's why we're asking that (the U.S. government) clarifies this for us. A foreign government can't provide money to political groups," he said.
Later asked if he believed Washington was seeking to remove him from office, he said he did not think that was the case.
Washington has expressed concern over record number of undocumented immigrants arriving at the southern border. An influx is expected to increase as the weather warms.
Border authorities stopped around 170,000 people trying to enter the US illegally in March, a 20-year high.
The number of unaccompanied children in particular have surged, with photos of migrant shelters showing children crammed together in poor conditions circulating on media platforms.
In February, the White House said it would start phasing out Trump's Migrant Protection Protocols (MPP). The program had forced thousands of asylum seekers to wait in Mexico for their asylum cases to be heard.
The US border remains closed to most asylum seekers under the Trump administration's COVID-19-related order. Biden has not revoked the order.
About two-thirds of US adults said the Biden administration was doing a very bad or somewhat bad job of dealing with the increased number of people seeking asylum, according to a May survey from the Pew Research Center.
Harris has said she will visit Mexico and Guatemala on June 7-8 for her first trip abroad as vice president.