Concerns are mounting among legislators as several of the country’s major airports faced significant delays over the weekend, attributed to a shortage of air traffic control staff. This comes as the government shutdown looms into its fourth week.

Although air traffic controllers are classified as essential personnel and must continue working, they are currently doing so without receiving pay.

Lawmakers are paying close attention to the weekend’s disruptions and the growing threat of “sick-outs” by controllers, recognizing that travel setbacks might be the catalyst needed to bring about negotiations.

Senator Mike Rounds (R-S.D.) remarked, “This situation is unlikely to improve over time. As the shutdown drags on, frustration will only grow among those missing paychecks, and naturally, their discontent will increase.”

Rounds further commented, “Many will seek ways to express their dissatisfaction, despite understanding the serious consequences of calling in sick and causing delays. I understand their predicament.”

Unlike other parts of the federal workforce, air traffic controllers could have a say in ending the three-week long shutdown — but at a major cost. Travel delays are among the shutdown effects felt most directly by average Americans, and the absence of fewer than a dozen controllers helped force the government to reopen in 2019 as it prompted a ground stoppage of flights at LaGuardia Airport in New York. 

“Air traffic controllers had a pretty powerful punch,” Senate Minority Whip Dick Durbin (D-Ill.) said of those actions. 

The Federal Aviation Administration said on Monday that there were “increased staffing shortages across the system” the day prior, which caused delays at airports in Atlanta, Chicago, Dallas and Newark, N.J. 

According to FlightAware, there were 19,000 flights that were delayed between Saturday and Monday, with Sunday marking the high mark at nearly 8,000 delays. There were also 1,600 flight cancellations during that span. 

Southwest Airlines saw more than 30 percent of its flights delayed on Sunday and Monday, with American Airlines seeing a similar figure on Sunday as well. 

Overall, 13,000 air traffic controllers and 50,000 Transportation Security Administration officers are working without pay this month.

“It’s certainly something I’m concerned about,” said Sen. Andy Kim (D-N.J.), who represents Newark Liberty International Airport (EWR), which has its own issues this year without factoring in the shutdown. “We already have low staffing, so this is something I’ve been worried about writ large. We see how devastating those disruptions can be on a number of fronts which is why I’m frustrated.” 

Transportation Secretary Sean Duffy acknowledged on Monday morning that more of these issues could be coming down the tracks. 

“I hope we don’t see more disruptions. But as this gets closer to payday, I think you could see more of that through the airspace,” Duffy told Fox News. 

This is not the first sign of trouble since the start of the shutdown. More than 23,000 delays were reported between Oct. 6 and 10, many of which also stemmed from air traffic controller tumult.

At the time, Duffy noted that 53 percent of delays were due to staffing issues, compared with five percent normally. 

Durbin told reporters on Monday that he inquired with TSA workers at Chicago O’Hare International Airport (ORD) while traveling back to Washington about issues in recent days. He said they reported a “slowdown” on Sunday, but that the airport was back to “full tilt” on Monday.   

Those were not the only issues the airport experienced in recent days. A pair of United Airlines planes clipped wings at O’Hare on Friday while one of them was taxiing to a gate to deplane. 

Senate Majority Leader John Thune (R-S.D.) is expected to hold a vote this week on a bill to pay “excepted” employees — those who are deemed essential during the shutdown. That also includes 1.3 million members of the military. 

Thune told reporters that the vote will happen either Wednesday or Thursday. 

Federal workers are also set to miss their first full paycheck on Friday, having received a partial one earlier in the month. 

While lawmakers remain worried about a continued spate of delays and cancellations, there is something worse that they are praying can be avoided amid potential “sick-outs.” 

“If there were — heaven forbid — some accident that might be associated with this problem, there’d be hell to pay,” Sen. John Cornyn (R-Texas) told The Hill. “That’s for sure.”