Originally Published: 21 DEC 23 13:10 ET

Updated: 21 DEC 23 14:02 ET

By Priscilla Alvarez, CNN

Washington (CNN) — President Joe Biden is ramping up the pressure on his Mexican counterpart to help with the untenable situation at the US southern border that’s left officials scrambling to respond to an unprecedented migrant surge and exacerbated one of the president’s longstanding political problems.

Biden spoke with Mexican President Andres Manuel Lopez Obrador Thursday morning as the US seeks additional assistance to drive down the number of migrants arriving at the US-Mexico border. The call comes at a politically delicate moment for Biden, who has repeatedly grappled with migrant surges fueled by deteriorating conditions in the Western Hemisphere.

In their call, the two presidents agreed that “additional enforcement actions are urgently needed” to reopen ports on the US-Mexico border where a migrant surge has strained federal resources and led to port closures, National Security Council spokesman John Kirby told reporters.

“They had a chance to talk about ongoing efforts to manage the unprecedented migratory flows in the Western Hemisphere – building on the Los Angeles declaration for migration and protection,” Kirby said, referring to the call between the two leaders earlier Thursday.

Senior US officials, including Secretary of State Antony Blinken, Homeland Security Secretary Alejandro Mayorkas and White House Homeland Security Adviser Liz Sherwood-Randall, will travel to Mexico in the “coming days” to discuss further actions with Mexican officials, Kirby said.

Border security — which remains a vulnerability for Biden in 2024 — has been at the forefront this month as Senate negotiators tried to reach an immigration deal tied to the administration’s national security supplemental request. Those talks stalled, keeping Biden from clinching additional aid to Ukraine and Israel before the end of the year. The White House request also included $14 billion for border security.

Former President Donald Trump, meanwhile, has escalated his already virulent anti-immigrant rhetoric and Republican Gov. Greg Abbott of Texas escalated his transport of migrants to Democratic-led cities by flying migrants to Chicago, which will host the Democratic National Convention next summer.

Taken together, the situation underscores the headwinds ahead for Biden as he faces criticism from Republicans who say he’s to blame for the border crisis, Democrats who argue more can be done to handle the surge and progressives who are pushing back against stringent border measures.

Biden administration officials have repeatedly cited the record movement of migrants across the Western Hemisphere as a regional issue that requires help from multiple partners. But despite a series of measures by the US to try to curb the flow of migrants, thousands have arrived at the US southern border.

Over recent days, more than 10,000 migrants have unlawfully crossed the US-Mexico border daily — numbers not seen since days before the lifting of a Covid-era restriction known as Title 42 that allowed authorities to turn back migrants at the border. The lack of capacity and resources to address them is amounting to the type of scenario US officials once planned for but hoped wouldn’t materialize.

Under the Biden administration, the Department of Homeland Security considered multiple scenarios and planned for surges at the US southern border as high as 16,000 to 18,000 arrivals a day, ahead of the lifting of the Covid-era border restriction that officials worried would prompt a surge.

“We could have — and we could sustain — a couple days at 12,000 encounters,” a former Homeland Security official told CNN.

“But the reality is that a sustained flow of 12,000 to 14,000 is what we determined would buckle the system. Anything beyond that started a significant strain of resources and detention. Ultimately, we knew we were surpassing the capabilities of DHS,” the former official said. “It will break.”

What makes this moment uniquely challenging, officials say, is that multiple sectors along the US southern border are overwhelmed, making it more difficult to decompress the areas of the border that are grappling with large groups of migrants.

“When you have multiple sectors and you can’t decompress because the places you normally decompress to are overwhelmed, it’s untenable,” said former US Border Patrol Chief Raul Ortiz.

A Homeland Security official stressed that the situation at the US-Mexico border, where personnel are being moved around to try to absorb the flow of migrants and thousands of people are waiting to be processed, nears a “breaking point.”

The nationalities and demographics of migrants have also consistently presented a challenge for authorities because there isn’t enough detention space or repatriation flights for those who don’t qualify for asylum.

The surge, according to border officials, is being driven by pseudo-legitimate travel agencies and organized transportation networks that are advertising travel to the US southern border and ultimately connecting migrants to smugglers.

This week, there were more than 26,000 migrants in Customs and Border Protection custody — nearly 10,000 people over capacity.

Abbott has seized on the growing number of arrivals at the border, transporting migrants who have been processed and released pending their immigration proceedings to cities including New York, Washington, Denver, and Chicago. The move, while driven by Abbott, has been a point of contention between Democratic officials and the White House as cities grapple with an influx of arrivals.

Abbott escalated his efforts Wednesday when the state flew migrants to Chicago. The flight departed from El Paso to Chicago with 120 passengers.

The White House slammed Abbott on Thursday for flying migrants to Chicago, calling it a “political stunt” that “adds to his tally of extreme policies which seek to demonize and dehumanize people.”

“Yet again, Governor Abbott is showing how little regard or respect he has for human beings,” White House spokesperson Angelo Fernandez Hernandez said in a statement to CNN.

“Governor Abbott leaves migrants on the side of the road in the dead of winter, installs razor wire making it more dangerous for Border Patrol to do their jobs, and promotes extreme laws that will make communities in Texas less safe. Governor Abbott is not interested in solutions, he only seeks to use people as political pawns,” he added.

The-CNN-Wire