Some US airports may have to shut as travellers endure long wait times at security following a shutdown that's seen 50,000 staff go unpaid.
The acting head of the Transportation Security Administration (TSA) said it was a "dire situation".
Ha Nguyen McNeill said nearly 500 TSA employees - who screen passengers and luggage - had quit so far after not receiving pay since mid-February.
She said multiple major airports were seeing 40% to 50% call-out rates (a measure of absence), compared with an average of 4% normally, because staff "simply cannot afford to report to work".
"This has led to the highest wait times in TSA history, with some wait times greater than 4.5 hours," she added.
A resolution does not appear imminent, as Democrats and Republicans still cannot agree on a deal on funding the Department of Homeland Security, the body that encompasses the TSA.
Democrats want changes to immigration and deportation operations after the controversial killings of two people in Minneapolis earlier this year by Immigration and Customs Enforcement (ICE) officers.
ICE agents have been sent to some airports by the Trump administration for what Ms McNeill called "non-specialised screening functions", but opponents say the move is inflammatory.
'Staff are sleeping in their cars'
In the meantime, many TSA workers are being pushed to the brink and are resorting to desperate measures.
"Some [staff] are sleeping in their cars, selling their blood and plasma, and taking on second jobs to make ends meet, all while being expected to perform at the highest level when in uniform to protect the travelling public," Ms McNeill told the House Homeland Security Committee.
She said assaults had also increased by 500% since the shutdown began in mid-February, as some passengers take out their frustrations on staff.
The boss of Houston airport warned security waits of up to four hours could get longer if a deal isn't done soon.
In a video on the airport's website, Jim Szczesniak said employees working in areas such as IT, finance and maintenance had been redeployed to try to manage the lines. However, he warned it wasn't sustainable.
New York LaGuardia was another airport seeing long lines on Wednesday afternoon, with people queuing virtually the entire length of Terminal B.
Read more from Sky News:
BBC announces new director-general
Woman jailed for conning men on dating sites
The TSA boss also agreed during her committee appearance that there could be problems when fans arrive for the World Cup in June.
Ms McNeill said it took four to six months to train new staff and added that job applications had dried up significantly, raising questions about replacing those who have quit.
Meanwhile, the White House has rejected Elon Musk's offer to pay TSA wages during the shutdown, according to CBS News.
The world's richest person made the offer on X at the weekend.
(c) Sky News 2026: US airports may have to shut as passengers endure 'highest wait times in history', transp
Gang-rape victim, 25, to be euthanised after father's legal challenge fails
UK facing biggest economic hit from Iran war of any major country
Transgender women athletes banned from female Olympic events
Labourer who killed mother-of-two and buried her in shallow grave jailed for 18 years
'Transfer trick' couples can use to pay less tax | Money newsletter