Flight delays continued across U.S. airports Sunday due to air traffic controller shortages as the government shutdown entered its second month, with Newark airport facing two- to three-hour delays.

Delays at Newark were affecting other regional airports, according to New York City’s Emergency Management office, prompting travelers to check flight status and expect longer waits.

Major airports in Houston, Dallas, Chicago, San Francisco, Los Angeles, Denver, and Miami also experienced delays and some cancellations, with FlightAware reporting 4,295 delays and 557 cancellations nationwide.

Transportation Secretary Sean Duffy said he does not plan to fire controllers working without pay, emphasizing they need support rather than punishment, the AP has reported.

The FAA has nearly 13,000 controllers working without pay, adding to an existing shortage of about 3,000, which continues to strain air traffic management.