Portions of U.S. airspace may be forced to close if the government shutdown continues into next week warns the U.S. Department of Transportation.

Sean Duffy, Department of Transportation (DOT) Secretary, said this could result in “mass chaos,” such as large-scale flight delays and cancellations, if staffing shortages among air traffic controllers worsen. 

Nearly half of major air traffic control facilities operated by the Federal Aviation Administration are experiencing shortage of staff and 13,000 air traffic controllers are working without pay.

“These hard-working Americans have bills to pay, and they are being forced to make decisions and choices,” Duffy said “Do they go to work as an air traffic controller, or do they have to find a different job to get resources, money, to put food on their table, to put gas in their car? And as every day goes by, I think the problem is only going to get worse, not better.” 

At the FAA’s largest 30 airports, “anywhere from 20 to 40% of our controllers aren’t coming to work,” according to FAA Administrator Bryan Bedford. (RELATED: Wisconsin Declares State of Emergency As Democrats Continue Government Shutdown)

More than 1,800 flights traveling within, to, and out of the U.S. were delayed on Nov. 4, and more than 50 were canceled, according to FlightAware.com. 

There were more than 5,000 flights departing and arriving at U.S. airports delayed on Sunday, Nov. 2. (RELATED: Waukesha Alderman No Longer Teaching at Catholic Memorial After False ICE Claim)

While the Democrats blame Republicans for the shutdown, Duffy blamed the Democrats in a Nov. 4 press conference. 

“We have the safest, most efficient airspace in the world,” Duffy said. “Not because of that equipment, because of men and women who sit in those towers, TRACONs, and centers and keep our system safe, keep it efficient, and those are the very people Democrats have refused to pay. I find it unacceptable and Democrats should do their job. Fund the government, open it up, and let’s get back to work.”