A crush of Americans are seeking to travel overseas again as vaccination rates climb in the U.S., and foreign governments loosen their restrictions. But many of them are running into a critical problem: Their passport is expired.
That's led to another crush -- of passport applications -- one that has overwhelmed the State Department's 26 passport agencies across the country and created an enormous backlog of applications.
For Americans planning to travel abroad, the agency warned they should submit an application at least six months in advance.
The lengthy delays in processing have left many Americans unable to travel, sparking public frustration, as well as concern from Congress. Two top lawmakers urged the State Department this week to expedite applications and cut down the "well beyond usual processing times."
The State Department now says passports submitted through the mail for renewal can be expected back in up to 18 weeks, or 12 weeks if an applicant pays extra for expedited processing. It's unclear how many applications in total are backlogged -- a number that was previously available to the public.
For Americans who want to apply in-person, most of the offices across the country still have very limited appointments, reserving them for life-and-death emergencies. The State Department said it is returning staff to offices still, even though many cities across the country are already fully reopened.
"We continue to adapt to the COVID-19 situation while we work to meet demand as U.S. citizens increasingly seek to travel overseas again," a State Department spokesperson told ABC News.
Over the summer, the agency is returning more than 150 staffers to work in 21 of its domestic offices, according to the spokesperson, who said that will increase their capacity and process applications more quickly.
"It will take time for us to ramp back up though," they added.
The State Department also blamed its delays, in part, on another federal agency -- the U.S. postal service. In a notice Monday, it said mail delays mean it can take up to six weeks for its passport officials to receive an application or send out a new passport.
"We continue to work to reduce processing times for both routine and expedited service, while protecting the health and safety of our staff and customers," the agency said in its notice Monday.
The long delays and angry constituents have caught the attention of Congress, with several top lawmakers now demanding that the department cut down on those wait times and expedite Americans' passport applications.
"It is critical that the Department use all available tools to reduce extended processing times, including strategies developed to address past passport backlogs," wrote Rep. Gregory Meeks, D-N.Y., and Rep. Michael McCaul, R-Texas, the top Democrat and Republican on the House Foreign Affairs Committee, in a letter to Secretary of State Antony Blinken Monday evening.
Lawmakers have been urging the agency to fully re-staff the 26 regional offices so that they can process applicants at full capacity and can accept walk-ins, provided that local restrictions allow that.
The State Department is expected to brief lawmakers on its efforts Thursday, according to a congressional aide.
ABC News' Amanda Maile contributed to this report.