On his visit to the U.S.-Mexico border this week, President Biden rued the death of the bipartisan Senate border policy bill, called on former President Trump to join him in calling for the bill’s revival and tried to flip the script on his weakest issue. But he did not sign a much-prognosticated executive action to crack down on asylum.

Presidential power on immigration and border policy is expansive, but multiple administrations have hit a brick wall with court challenges blocking executive efforts to work around legislative impasses.

Republicans including Speaker Mike Johnson (La.) have chided Biden for not taking enough executive steps to address conditions at the border, but the administration has few short-term tools left.

For instance, the Biden administration has already tightened asylum regulations, though without extra funding to implement those restrictions, they have little effect on everyday enforcement.

“When we’re talking about piling restrictions on restrictions, if you don’t have the funds to implement them, then the same challenges arise,” said Kathleen Bush-Joseph, a policy analyst with the U.S. Immigration Policy Program at the Migration Policy Institute.

The Biden administration shocked immigration advocates when it implemented its “Circumvention of Lawful Pathways Rule,” essentially a rule making it harder for people who cross the border without authorization to apply for asylum.

That rule, first implemented in May amid a doom-and-gloom frenzy over the end of Title 42, was immediately challenged in court by advocacy groups including the ACLU, who derided it as an “asylum ban,” a moniker rejected by the administration.

Despite the lawsuits and public controversy, the rule didn’t change much on the ground.

“In order to carry out an asylum ban rapidly at the border, you need asylum officers who can apply that ban as part of the credible fear process. And if you don’t have enough asylum officers, then that ban cannot be applied at the border and has to be applied years later in immigration court,” said Aaron Reichlin-Melnick, policy director at the American Immigration Council.

“So until you fix those fundamental restrictions, fundamental resource limitations, you just cannot apply these quick asylum denial processes to the majority of migrants.”

Both the Biden and Trump administrations have dealt with the same core problem amid rising migration in the Western Hemisphere: The asylum system does not have the capacity to quickly process hundreds of thousands of people a month and determine who is eligible for protection.

Because of sheer numbers, wait times to determine eligibility stretch into years, and successive administrations have determined it is neither practicable nor desirable to indefinitely detain hundreds of thousands of people, including children.

Asylum applicants are therefore released within U.S. borders, in many cases with eligibility to apply for work permits, pending their immigration court cases.

To speed up that process or to generally redirect border enforcement, the executive needs cash.

“There are some hard limitations on where the president can get money from. We saw this with the Trump administration with the taking of [Defense Department] funds to build the border wall, that’s something that some judges actually ruled was unlawful,” said Reichlin-Melnik.

“Those cases ended – they never made their way to the Supreme Court because the Biden administration won [the 2020 election], and the cases were mooted out. But you may have eventually have the Supreme Court ruling that the funding was not lawful.”

Biden’s pitch for the defunct bipartisan Senate deal rests largely on budgetary grounds.

In his visit to Brownsville, Texas, on Thursday, Biden called on Trump to back the deal, which was built on the structure of a White House supplemental budget request that would have greatly expanded both enforcement and processing.

“They desperately need more resources,” the president said of U.S. border agencies. “They need more agents, more officers, more judges, more equipment in order to secure our border.”

On the same trip, Homeland Security Secretary Alejandro Mayorkas praised the Senate deal, for which he provided “technical and operational expertise.”

But Mayorkas also brushed aside any suggestion that Biden would announce executive actions.

“There will not be any executive actions announced today. As I continue to say, the legislation is what we need. It is the enduring solution. Actions taken outside of legislation are often met with litigation challenges in court,” said Mayorkas.

He also said the administration would not implement an order based on Section 212(f) of the Immigration and Nationality Act.

The Trump administration implemented a proclamation based on the statute, known as the Muslim ban, which lasted from 2019 to 2021.

But the proclamation lacked teeth, and an accompanying Department of Homeland Security and Department of Justice regulation to enforce it was shut down in court because it violated the basic precept of asylum law — that all foreign nationals on U.S. soil are allowed to apply for asylum.

“The Supreme Court upheld the third version of that, but that was about preventing people who would have been flying into the country, so people are getting visas and refugees,” said Bush-Joseph.

“And the whole difference here is that with the southern border, I don’t see how the president can — absent congressional action — quote-unquote, ‘shut down the border.'”

Republicans such as Johnson, however, are pushing one Trump-era policy that showed more resilience against legal challenges: “Remain in Mexico.”

“There is no direct obstacle from the U.S. legal system at the moment that would prevent the Biden administration from restarting the Remain in Mexico program,” said Reichlin-Melnick.

There is ongoing litigation over the Biden administration’s decision to end the program, but Remain in Mexico – formally known as the Migrant Protection Protocols (MPP) – faces political, diplomatic and humanitarian challenges, as well as legal constraints on the Mexican side of the border.

“A Supreme Court decision on the Mexican side … said that if Mexico were to do something like MPP again, then they would actually have to put in place rules or regulations for the safety and well-being of migrants because of what happened last time,” said Bush-Joseph.

“It’s not just about what’s legal on the U.S. side, it’s also about what’s legal in Mexico, and what would need to happen for them to have the political will to put it in place and then what legal steps they would have to go through.”

Mexican President Andrés Manuel López Obrador is unlikely to acquiesce to such a program, though he did in 2019 after Trump threatened to impose unilateral tariffs.

Mexico will have a presidential election in June, and though López Obrador’s chosen successor, former Mexico City Mayor Claudia Sheinbaum, is running ahead in the polls, López Obrador is likely to avoid folding in the face of U.S. interests.

He is even less likely to accept a return of the program after Johnson publicly said he’d essentially dared Biden to impose the policy against Mexico’s wishes.

And like other border executive actions, Remain in Mexico did not work as intended.

Instead of releasing asylum applicants into the United States, migrants selected for Remain in Mexico were given court dates and expelled back into Mexico.

The program drained resources from both U.S. and Mexican border officials, who had to process asylum seekers attending their U.S. immigration court appointments, and it further contributed to backlogs among those asylum seekers who were not in the program and were released into the United States.

At its peak, Remain in Mexico processed around 20,000 migrants a month – a fraction of the number arriving monthly at the border.

“Of course, 20,000 people is nothing, and the United States does not have anywhere close enough to the ability to shift that number of resources to the border,” said Reichlin-Melnik.

On the flip side, the Biden administration has also tried to expand pathways to entry for migrants in an attempt to regulate the existing flow of people.

The administration has centered its efforts on that end on expanded use of parole, a program to more quickly process nationals of Cuba, Haiti, Nicaragua and Venezuela, and improvements to the CBP One app, which helps migrants schedule appointments at ports of entry.

The administration has also expanded use of Temporary Protected Status (TPS), a program that allows nationals of certain designated countries to live and work in the United States for a period of time.

But by and large, programs focused on making it easier for migrants to arrive have largely faced similar legal, budgetary and logistical challenges as enforcement policies.

Advocates have called on the Biden administration to improve coordination among NGOs, state and local authorities as an escape valve to better onboard the new arrivals, given the lack of options at the border.

The administration has congressional authorization to fund the Shelter and Services Program, which in turn funds non-governmental shelters for migrants, and it has expanded efforts to help eligible migrants more quickly process their work permits.

But the administration has so far shied away from proposals for broader federal coordination that could direct migrants to parts of the country with sufficient services and with demographic needs.

“There are communities across the country right now that are saying ‘we actually would love for migrants to show up here.’ And you’ve seen some cities like St. Louis, for example, has actually opened up its doors and said ‘we would like more migrants to come here, because we have a desperate need of more people,” said Reichlin-Melnick.