Amid an unprecedented surge in demand for U.S. passport processing, the State Department is expanding its application-processing call-center hours on weekends, as at least one U.S. senator says the agency should take additional measures to staff up.

In a statement to NBC News, a Department official said the agency is now offering weekend call-center service Saturdays and Sundays from 10 a.m. to 3 p.m. ET.  

The spokesperson said the agency has also tripled the number of phone lines available at the National Passport Information Center, and that it is "aggressively" hiring and training additional staff to handle the influx of calls it continues to receive.

The Department said this month that it is experiencing a surge in passport demand this year, with approximately 400,000 applications coming in each week. That is only down slightly from the more-than 500,000 applications a week it was receiving in the first half of the year, as American international travel soars this summer.

Overall, the State Department expects to receive nearly 2 million more applications this fiscal year than in its previous record-setting, pre-pandemic year in terms of applications.

The Department is advising passport applicants to apply at least six months in advance of their departure date.

Following a visit Friday to a passport processing center in Washington, Sen. Mark Warner, D-Va., told NBC that he was sympathetic to Americans' frustrations.

"We have to do better," he said, adding, "You shouldn’t have to wait three hours on the phone."

While he said it was evident from his visit that department officials were working as hard as they could, he said the agency should be looking to hire as many workers as possible for call-center positions, since those don't require security clearances.

"We ought to be able to have that surge capacity. ... You shouldn't have to call your senators," Warner said, though he also believed the biggest demand wave had passed.

A call to both his U.S. senators and his representative has failed to produce results for Jhonas Amulacion, a Spokane, Washington, resident who has been planning since last year to visit his family in the Philippines this summer with his partner.

They submitted their applications in early May and paid the $60 expedited-processing fees.

So far, they've received no updates about whether they'll get their documents in time. Amulacion is bracing for the possibility of having to travel to Seattle — an approximately four-hour drive — for a last-minute in-person appointment.

He said such a trip would already add to the thousands of dollars they paid for their plane tickets — though luckily those are refundable — and the hours spent waiting on hold before dawn to reach a customer-service representative first thing in the morning.

A State Department spokesperson said in an email that customers like Amulacion and his partner would be eligible for a refund of their $60 if they failed to receive their documents in time.