Immigration and Customs Enforcement has drafted contingency plans to cut detention capacity and release thousands of immigrants as a result, according to a source familiar with the plan.

The draft plan comes as ICE faces a dire budget shortfall amid stalled congressional action on the White House supplemental request.

The Department of Homeland Security has grappled with record levels of migrants at the US-Mexico border over the last year, draining federal resources and funds and prompting a White House ask for $14 billion in border security funding as part of a broader national security request. The supplemental provided $7.6 billion for ICE.

President Joe Biden has repeatedly implored Congress to give him more resources to deal with the situation at the US-Mexico border, assigning blame on Republicans for not doing more.

“Giving up on real solutions right when they are needed most in order to play politics is not what the American people expect from their leaders. Congress needs to act to give me, Secretary Mayorkas, and my administration the tools and resources needed to address the situation at the border,” Biden said in a statement Tuesday, blasting the House GOP for impeaching Secretary Alejandro Mayorkas.

ICE – the immigration enforcement arm under DHS – has historically been underfunded and is now staring down a $700 million deficit, according to the source, resulting in discussions that include slashing detention space. Detention facilities and deportation flights are among the priciest budget items for ICE.

The Washington Post first reported the draft plans.

“The Administration has repeatedly requested additional resources for DHS’s vital missions on the southwest border and Congress has chronically underfunded them,” a Homeland Security spokesperson said in a statement.

“Without adequate funding for CBP, ICE, and USCIS, the Department will have to reprogram or pull resources from other efforts,” the spokesperson said, adding that ICE won’t be able to sustain its current operational tempo.

Over recent years, ICE has assisted Customs and Border Protection in its border mission as that agency is also overwhelmed. In the past, when facing budget shortfalls, ICE has had to move money around within the agency, ask for reprogramming or rely on supplemental funds.

Those funds often come from non-immigration related agencies, including Coast Guard, the Transportation Security Administration, among others.

The agency detains immigrants with criminal backgrounds, those preparing for removal and those who fall under mandatory detention.

Border arrests dropped by 50% in January compared to December, according to newly released federal data. Homeland Security officials have attributed the decline to ongoing high-level talks between the US and Mexico, which has doubled down on enforcement, but caution that encounters historically drop in January before ticking up again.

CBP Commissioner Troy Miller conceded authorities still face hurdles on the border, saying in a statement: “We continue to experience serious challenges along our border which surpass the capacity of the immigration system.”

In January, the US Border Patrol reported 124,220 encounters along the US-Mexico border. Notably, there was a significant drop in Venezuelans – nearly 11,600 compared to 57,851 in December. Both the US and Mexico have restarted deportation flights to Venezuela.

Without additional funding, CBP may also need to repurpose funds and draw back some operations, according to DHS.