TUCSON, Ariz. (AP) — Inside giant white tents that house about 1,000 migrants near Tucson International Airport, Border Patrol agents demonstrate clockwork efficiency to release detainees within two days of arrest with orders to appear in immigration courts at their final destinations. Agents transmit information from the field to colleagues who prepare court papers while migrants are bused hours away to a processing center, minimizing time in custody.

Notably missing from the operations hub in the busiest corridor for illegal crossings into the U.S. are asylum officers who do initial screenings, which are intended to weed out weak claims that don’t meet narrowly prescribed grounds for seeking protection, such as race, religion and political opinion.

Asylum officers were instructed nearly a year ago to apply a higher screening standard on those who cross the border illegally after passing though another country, such as Mexico, but they are too understaffed to have much impact. The Biden administration hails the higher standard as a cornerstone of its border policy in legal challenges, but its application in only a small percentage of arrests shows how budgets can fail to match ambitions.

Strained budgets continue to loom large as the White House again considers sweeping measures to limit asylum at the border.

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The failure of a $20 billion spending plan on border security this month has caused the administration to assess its priorities. U.S. Immigration and Customs Enforcement, facing a $700 million hole this year, is considering cutting the number of detention beds from 38,000 to 22,000 and facilitating fewer deportation flights. These possible steps were first reported by The Washington Post and confirmed to The Associated Press by a U.S. official who spoke on the condition of anonymity because they were not authorized to discuss it publicly.

The failed spending package crafted by Senate negotiators would have given $4 billion to U.S. Citizenship and Immigration Services, including to add 4,338 asylum officers to screen applicants and make final decisions on claims — more than four times current staffing.

Arrests for illegal border crossings from Mexico plunged 42%, to the second-lowest monthly rate of Joe Biden’s presidency, a month after the higher standard replaced COVID-19 pandemic-related asylum restrictions. The rule “is working as intended and has already significantly reduced encounters at the border,” Blas Nuñez-Neto, assistant homeland security secretary for border and immigration policy, said in a court filing at the time.

Asylum-seekers subject to tougher screenings had a 59% pass rate through September, down from 85% in the five years before the pandemic, Nuñez-Neto said in another court filing that called the policy a success.

While that suggests the policy has made a difference, its scope has been limited. Officers interviewed only 57,700 migrants under the new rule through September, according to Nuñez-Neto. That represents only about 15% of the nearly 365,500 migrants released by Border Patrol from June to September with notices to appear in immigration court.

The Department of Homeland Security declined this week to provide more recent numbers. It insists that the higher screening standard is working as intended, while acknowledging it has failed to keep pace with unprecedented migration flows and calling on Congress to adequately fund the efforts.

Asylum officers did more than 130,000 screenings, known as “credible fear interviews,” at the border during the 2023 budget year, which was more than double the year before. But more than 600,000 migrants were released with notices to appear in immigration court in that time and another 300,000 with orders to report to an immigration office for a court date, a practice that has largely ceased.

Mbala Giodi, a migrant from Angola, waited hours after crossing the border from Mexico in the mountains east of San Diego for agents to take him to a holding station, where he spent two days. He was released at a San Diego transit center and told he would have a chance to explain his reasons for fleeing his southern Africa homeland in court, with an initial hearing scheduled in New York in May.

“There wasn’t much problem,” said Giodi, 42, who calls himself a victim of government repression for being a student protestor in Angola.

To even put the higher screening standard into effect, Citizenship and Immigration Services added about 1,000 staff to assist an existing 850 or so asylum officers, training former asylum officers and other employees for short stints, said Michael Knowles, spokesman for the National Citizenship and Immigration Services Council. The union represents workers at the agency, which also oversees work visas, green cards, citizenship applications and asylum claims that originate away from the border.

Assigning so many employees to border cases extended wait times for other services, he said. Weekend overtime was mandatory, as was holiday work.

“We’re so overwhelmed and there’s so much pressure,” Knowles said. “Part of the border crisis is they didn’t hire enough of us to do the work.”

A lack of resources hampered another Biden policy that took effect in June 2022, empowering asylum officers to make final rulings on claims, not just screenings. It aimed to ease the workload of immigration judges, whose backlog of more than 3 million cases has allowed asylum-seekers with weak claims to stay in the United States for years — with eligibility for work permits — while their cases wind through the system.

Fewer than 6,000 asylum cases had been decided under the 2022 policy by the end of September.

“That is a very important program that got very little support,” Knowles said.

Advocates for asylum-seekers have sued over application of the higher screening standard. They argue that it unfairly penalizes those who cross the border illegally while a heavily oversubscribed online appointment system, called CBP One, is virtually the only way to come through an official port of entry. The standard remains in effect while a judge’s ruling declaring the policy illegal is under appeal. The case may reach the Supreme Court.

While migration flows dropped immediately after the higher standard took effect, border arrests increased in five of the last six months of 2023 as migrants and smugglers adjusted to realities on the ground, peaking at an all-time high of 250,000 in December.