That massive backlog has angered some lawmakers. In a new letter obtained by ABC News, seven Republican senators offer a rare rebuke of the Trump administration for the State Department's "slow and inefficient policy" to process passports and its "unacceptable" and "inadequate" response to the challenge presented by the pandemic.
"This is ridiculous and cannot continue," said Sen. James Lankford, R-Okla., who spearheaded the letter. In a series of tweets last week, he accused the agency of "a major fumble [that] will hinder our economic recovery."
The backlog has built up in just 10 weeks since the agency severely curtailed passport services on March 19 to only "life-or-death emergencies." According to the report provided to Congress last week, the department has been receiving 9,000 passport applications each day, compounding the logjam.
A State Department spokesperson told ABC News that 95% of the agency's staff responsible for processing passports were sent home for their safety, forcing them to "temporarily [suspend] expedited passport processing and [restrict] service at U.S. passport agencies and centers to life or death emergencies and urgent cases."
Since then, the agency has issued more than 350,000 passports, according to the spokesperson, but the vast majority of them were handled in March, with just over 26,000 in April and May combined.
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State Department officials briefed lawmakers Thursday on a plan to reopen passport offices in phases, based on the conditions and health restrictions at a particular office.
But the plan "contains no innovative steps or processes to reduce the backlog. Simply resuming operations and processing applications at a normal pace until the Bureau of Consular Affairs is caught up is not an acceptable approach," wrote Lankford, along with Sen. John Cornyn, R-Texas, David Perdue, R-Ga., Kelly Loeffler, R-Ga., Kevin Cramer, R-N.D., John Boozman, R-Ark., and Mitt Romney, R-Utah.
The plan's three phases have not yet begun. In phase one, a limited number of staffers will return to work, with applications processed on a "first in, first out basis." Phase two would have most staff return to work, and phase three, all staff. But the plan does not lay out any steps to address the current backlog.
Instead it warns that even once all staff have returned under phase three there will still be delays because the current backlog will take months to work through, and even more Americans will begin applying for passports or passport renewal as global restrictions lift.
In a statement Friday, the State Department said it's unable to work through the backlog until those phases begin and people return to their offices.
"Processing passport applications requires us to review sensitive documents, such as birth certificates and other personal records, and to physically print and mail passport books and cards back to applicants. This means that our staff are not able to process passport applications from home," the agency said.
The group of senators rejected that, saying "More urgency is needed and more innovation is required." They argue that private businesses, congressional offices and other federal agencies have found creative solutions and offer some of their own, such as having "at least some elements of each passport review to be completed remotely" by employees on secure government systems.
If more is not done, the senators warned, the department could be "partially responsible for stifling international commerce at a time when our nation is eager to resume economic activity."
The State Department still has a global travel warning at its highest level -- urging Americans "Do Not Travel" overseas. Some countries have started to loosen their restrictions, although public health experts warn that lifting them too soon could cause new spikes in coronavirus infection rates.
On average, the department processes over 18 million passports each year.