The Federal Aviation Administration temporarily halted flights into New York’s LaGuardia Airport because of a shortage of air-traffic control staff, escalating the pressure on President Donald Trump and lawmakers to end the government shutdown.

A lack of workers at an air-traffic control facility in the Washington area prompted the FAA to stop inbound flights Friday to LaGuardia, one of the nation’s busiest transportation hubs. While the delay program known as a ground stop was lifted at 10:37 a.m. after an hour and 22 minutes, the disruption cascaded through East Coast airports such as Newark Liberty International and Philadelphia.

The airport snarls underscored signs of growing strain as the government shutdown dragged into the 35th day. Union leaders and U.S. airline bosses warned of the rising impact to the aviation system Thursday, with JetBlue Airways Corp. Chief Executive Officer Robin Hayes saying the situation was reaching a “tipping point.”

The FAA attributed the delays to “a slight increase in sick leave” and said that the effects on the aviation system were moderate. Neither the FAA nor the National Air Traffic Controllers Association union has said that the delays are due to the shutdown.

“We’ve mitigated the impact by augmenting staffing, rerouting traffic, and increasing spacing between aircraft as needed,” the agency said in an emailed statement. “The results have been minimal impacts to efficiency while maintaining consistent levels of safety in the national airspace system.”

Political Standoff

White House Press Secretary Sarah Huckabee Sanders said the president had been briefed on the situation.

“We are monitoring the ongoing delays at some airports,” she said in an emailed statement. “We are in regular contact with officials at the Department of Transportation and the FAA.”

The situation at LaGuardia comes as Congress and the president have failed thus far to come up with an agreement to reopen the government. After the Senate rejected two proposals on Thursday, new talks began among Majority Leader Mitch McConnell, Minority Leader Chuck Schumer and the White House.

“McConnell and I had a good conversation,” Schumer told reporters Friday morning. “We’re trying to get everyone involved to work something out.”

House Speaker Nancy Pelosi said on Twitter that the shutdown is “pushing our airspace to the breaking point.” She called on Trump to agree to reopen the government and “stop endangering the safety, security and well-being of our nation.”

Washington, Jacksonville

The FAA’s website identified one of the affected facilities as Washington Center, which oversees mostly high altitude flight routes in the central region of the East Coast. It’s located in Leesburg, Virginia.

A second high-altitude control center in Jacksonville, Florida, also had a higher-than-expected absentee rate due to illness, according to the agency. However, the FAA hadn’t experienced any delays as a result.

The FAA frequently uses a variety of air-traffic delay programs to keep the system functioning as efficiently as possible. They are mostly put in place to handle weather issues that reduce the number of planes that can land at an airport, but controller staffing can also trigger such delays.

While there is little evidence so far of safety risks, airline CEOs and labor leaders warned this week of an uptick in worrisome signs as workers face a second pay period without getting a salary.

TSA Impact

On Wednesday, 7.5 percent of U.S. airport security officers were off the job, more than double the 3 percent rate on the same day a year earlier, the Transportation Security Administration said in a statement.

Southwest Airlines Co. said it lost out on as much as $15 million in sales this month because of the shutdown, and CEO Gary Kelly called the closing “maddening.” Delta Air Lines Inc. said last week that the political standoff was costing it about $25 million a month.