WASHINGTON, United States (AFP) — Air travel in the United States (US)  could soon “slow to a trickle,” authorities warned Sunday as thousands more flights were cancelled or delayed and passengers faced chaos triggered by the federal government shutdown.

Transportation Secretary Sean Duffy said the number of flights being snarled or cut would multiply if the funding impasse between Democrats and Republicans continues while Americans gear up to travel for the Thanksgiving holiday later this month.

“It’s only going to get worse,” Duffy said on CNN’s “State of the Union,” a Sunday news talk show. “The two weeks before Thanksgiving, you’re going to see air travel be reduced to a trickle.”

On Sunday afternoon, more than 1,800 flights within the United States and to and from the US had been cancelled and there were close to 5,700 delays, according to data from FlightAware, a flight tracking platform.

Airports that were particularly hard hit included the three New York City area airports, Chicago’s O’Hare International Airport, and Atlanta’s Hartsfield-Jackson Airport.

Newark’s Liberty International Airport — a major northeastern US hub — was among the worst-hit. Twenty percent of flights due to leave were scrapped, and there were delays to 37 percent of outbound flights, FlightAware showed.

At LaGuardia Airport in New York City, nearly half of all flights were delayed.

Duffy warned that many Americans planning to travel for the November 27 holiday “are not going to be able to get on an airplane, because there are not going to be that many flights that fly if this thing doesn’t open back up.”

The Thanksgiving weekend also kicks off the busy winter shopping season on which many retailers rely.

– ‘Massive disruption’ –

Travelers expressed their frustration on social media. “Moral of the story, if you don’t have to travel and have a low patience threshold, don’t fly,” said one.

Sunday marked the 40th day of the record shutdown and the third day of flights being reduced at airports nationwide, after the Trump administration ordered reductions to ease strain on air traffic controllers working without pay.

“We’re going to see air traffic controllers, very few of them coming to work, which means you’ll have a few flights taking off and landing,” Duffy told Fox News Sunday.

“You’re going to have massive disruption (and) a lot of angry Americans.”

Duffy sought to blame Democrats for the high-stakes political standoff, but Senator Adam Schiff said Republicans were rejecting a “reasonable” compromise deal to end the shutdown.

“And the result from the Senate Republicans was ‘no,’ from the House Republicans ‘we are staying on vacation,’ and from the president ‘I’m going out to play golf,’ and that’s where we are while people are hurting,” Schiff said.

When asked whether Democrats would turn around and vote with Republicans, Schiff, a California Democrat, indicated that the issue of healthcare subsidies remained a sticking point in negotiations.

“No, I certainly hope it isn’t going to happen if millions of people are going to retain their health coverage and not have to pay these exorbitant premium increases,” Schiff said on ABC’s “This Week with George Stephanopoulos.”

“We need to end this. We proposed something, I think very reasonable. It was a compromise. Certainly wasn’t everything I want, which is a permanent extension of the tax credits,” he said, urging Republicans to allow “more time to work on this and reopen the government.”