U.S. President Joe Biden made a politically charged stop at the southern U.S. border Sunday before flying to a Mexico City summit set to be dominated by a growing regional illegal immigration and drugs smuggling crisis.

On his way to Mexico City, he stopped for several hours in El Paso, Texas, a city at the heart of the troubled border. This was his first trip to the southern frontier since taking office.

Biden met with U.S. officials at the Bridge of the Americas crossing, watching a demonstration of the latest border enforcement technology, as well as a customs sniffer dog. He later got out of his motorcade to inspect a section of the tall fencing that snakes between El Paso and its twin city Juarez on the Mexican side.

"They need a lot of resources. We're going to get it for them," Biden told reporters after his visit to the customs post.

Biden is under huge political pressure in the face of spiraling illegal border crossings and applications for asylum by people making perilous journeys from regional countries afflicted by poverty or severe crime.

Biden's visit sought to respond to Republican accusations that he has been ignoring the situation.

But meeting Biden off Air Force One at El Paso's airport, Republican Texas Governor Greg Abbott handed him a letter blasting the visit as "$20 billion too little and two years too late."

"You have violated your constitutional obligation to defend the States against invasion through faithful execution of federal laws," Abbott wrote in the letter.

Biden on Thursday tried to tackle the problem, which has bedeviled U.S. presidents for decades, by announcing an expansion of powers to expel people just showing up at the border without clearance. At the same time, a legal, strictly enforced pathway will be created for up to 30,000 migrants a month from Cuba, Haiti, Nicaragua and Venezuela.

The quota will be restricted to those who already have a U.S. sponsor, while anyone attempting to cross the border illegally will be expelled in coordination with Mexico.

U.S. Homeland Security Secretary Alejandro Mayorkas acknowledged the lack of deeper solutions, saying that we're just dealing with a broken system characterized with legislative gridlock.

However, Mayorkas said that since a peak in mid-December, the number of people crossing illegally in El Paso have "dropped precipitously" from around 2,000 people a day to 700.

Biden is scheduled to meet on Monday and Tuesday with his Mexican and Canadian counterparts one-on-one and also together to talk about issues including trade and illegal immigration. 

(With input from agencies)