US officials revealed that they had released hundreds of detained immigrants in recent days to trim expenses ahead of massive automatic budget cuts due to take effect this week.
With three days to go before the so-called "sequester" -- $85 billion in across-the-board cuts -- takes effect, federal agencies are tightening belts as feuding lawmakers appear unable to reach a better-tailored deal.
Noting the "fiscal uncertainty" generated by the looming onset of the cuts, US Immigration and Customs Enforcement (ICE) spokeswoman Barbara Gonzalez said the agency had been forced to act.
"Over the last week, ICE has reviewed several hundred cases and placed these individuals on methods of supervision less costly than detention," she said in an email to AFP.
"All of these individuals remain in removal proceedings. Priority for detention remains on serious criminal offenders and other individuals who pose a significant threat to public safety."
The ICE, which is charged with deporting undocumented immigrants, is holding around 30,000 detainees across the country, agency sources told AFP.
The agency carried out a record 1.2 million deportations during President Barack Obama's first term. There are an estimated 11 million undocumented workers in the United States, many of whom have lived here for several years.
A bipartisan group of senators has been working to craft an immigration reform bill, with many Republicans keen to shore up Hispanic support after massively losing the key demographic to Obama in last year's election.
But the immigration effort is one of the few issues where bipartisan agreement may be possible in a bitterly divided Washington that has thus far been unable to avert the almost universally unpopular sequester.
The automatic cuts, agreed upon during the tense 2011 budget standoff, were intended as a poison pill that would force lawmakers to reach across the aisle and strike a more palatable compromise to trim the bloated national debt.
But Republicans, who control the House of Representatives, have refused to approve any new revenue while Obama and his fellow Democrats have called for a "balanced approach" of spending cuts and the closing of tax loopholes.
Republican champions of small government have welcomed the sequester cuts in principle but objected to cuts in defense and other programs they support.
Representative Bob Goodlatte slammed the release of the detainees and joined fellow Republicans in accusing the White House of scare tactics.
"It's abhorrent that President Obama is releasing criminals into our communities to promote his political agenda on sequestration," he said.
House Homeland Security Chairman Michael McCaul, another Republican, accused the administration of using the sequester to return to a "de facto catch-and-release policy" on illegal immigrants.
"While cutting spending is crucial, letting potentially dangerous detainees out of federal custody is not a responsible option," McCaul said in a statement.
"A reduction in (the ICE's) bloated administrative budget, which includes worldwide conferences costing millions of dollars, would cover the cost of keeping these detainees in federal custody."
Homeland Security Secretary Janet Napolitano has meanwhile warned that the sequester would result in the equivalent of 5,000 fewer border patrol agents, out of a total force of 21,000.