Denver International Airport air traffic controllers reported staffing shortages were impacting operations Tuesday afternoon and may cause flight delays, according to the Federal Aviation

U.S. Transportation Secretary Sean Duffy warned Tuesday that he may be forced to close parts of the nation’s airspace if the federal government shutdown continues for much longer.

U.S. officials delayed a new round of flights on Monday as airlines said 3.2 million air passengers have been hit by delays or canceled flights due to a spike in air traffic controller absences amid a lack of pay as the government shutdown entered its 34th day.

For the second consecutive day, flights into Austin-Bergstrom International Airport are likely to experience widespread delays due to air traffic control staffing shortages as controllers at the airport continue to work without pay.

Travelers going in and out of LAX are once again dealing with delays as employees continue to call out amid the ongoing government shutdown.

The ground stop impacted about 820 flights, with maximum delays of 66 minutes and average delays of 33 minutes