Atlanta-based Delta Air Lines is calling on Congress to reopen the government and pay air traffic controllers, TSA, and CBP officers across the country.

On Tuesday, air traffic controllers and other federal aviation workers missed their first full paycheck, leading to concerns about the impact on flights.

Recent absences have led to a number of isolated delays around the country because the Federal Aviation Administration was already extremely short on controllers prior to the shutdown. The FAA restricts the number of flights landing and taking off at an airport anytime there is a shortage of controllers to ensure safety.

Delta joined United, American, and Southwest to push Senators to "immediately pass a clean continuing resolution to reopen the government," a spokesperson for the airline told CBS News Atlanta.

"Missed paychecks only increases the stress on these essential workers, many of whom are already working mandatory overtime to keep our skies safe and secure. It's thanks to these federal employees that Delta is able to carry more than 500,000 daily customers on 5,000 daily flights," the spokesperson said. "A system under stress must be slowed down, reducing efficiency and causing delays for the millions of people who take to the skies every day."

The number of controllers calling in sick has increased during the shutdown, both because of their frustration with the situation and because controllers need time off to work second jobs instead of continuing to work six days a week like many of them routinely do. Transportation Secretary Sean Duffy has said that controllers could be fired if they abuse their sick time, but the vast majority of them have continued to show up for work every day.

While air traffic controllers still work without pay, Delta confirmed with CBS News that it has "arranged for a limited number of meals for transportation sector workers," but noted that it was operating "within the strict rules established for employees of federal government agencies."

Now on Day 31, pressure has continued to build on Congress to reach an agreement. During the 35-day shutdown in President Donald Trump's first term, the disruptions to flights across the country contributed to the end of that disruption. But so far, Democrats and Republicans have shown little sign of reaching a deal to fund the government.

The Associated Press contributed to this report.