The Biden administration will pause its program to send Americans free at-home COVID-19 tests this week, blaming Congress for failing to fund further rounds of shipments.

Americans who have yet to request all 16 of their free tests through the federal portal have until Friday to place their orders.

“Ordering through this program will be suspended on Friday, September 2 because Congress hasn’t provided additional funding to replenish the nation’s stockpile of tests,” the Department of Health and Human Services says on the page.

Since ordering opened up in May for a third round of free COVID-19 tests, the U.S. Postal Service has been allowing households across the country to request up to three orders of free tests, for a total of 16 tests.

Through the website, a senior administration official says the federal government has distributed more than 600 million free tests to date. The remaining stockpile of tests is being held back until later this year, in preparation for a “new rise in infections and more acute need.”

The official said federal health authorities “will expeditiously resume distribution of free tests,” if Congress comes through with more funding.

The Biden administration also opened up orders in June for at-home tests specifically designed to work with a smartphone application accessible for Americans who are blind or have limited vision.

However, citing “a significant increase in demand” for the tests, the department says those accessible tests are too now “temporarily out of stock.”

Back in January, the Biden administration had contracted for up to 500 million free at-home tests to be shipped nationwide from several manufacturers.

A request from the White House to fund this and other continuing COVID-19 response efforts has been stalled for months in Congress, prompting warnings from federal health officials of “significantly diminished domestic testing capacity” as manufacturers shutter their supply lines.

Other federal efforts to cover free COVID-19 testing are also now winding down.

The Centers for Disease Control and Prevention’s Operation Expanded Testing, which provided free lab tests to places like schools and shelters, will stop offering the service at the end of the year. A program from the Health Resources and Services Administration to reimburse providers for giving testing to uninsured Americans lapsed in March, “due to a lack of sufficient funds.”

For people with private insurance or Medicare Part B coverage, plans are still required to cover up to eight tests per month through the end of the public health emergency. The current declaration is due to expire in October, though the Biden administration is expected to renew the emergency for at least another few months beyond that date.

A growing share of Americans have turned to at-home rapid tests, which the Food and Drug Administration now says needs up to three separate tests to rule out some SARS-CoV-2 infections. A feared winter surge of the virus could bring about more than a million hospitalizations and 181,000 deaths in the worst-case scenario, modelers say.

But in the wake of little movement on Capitol Hill towards funding the Biden administration’s COVID-19 efforts, White House officials say they have begun working to transition some parts of the response to the private market.

Government distribution of an COVID-19 antibody drug – Eli Lilly’s bebtelovimab – is already ending this month, after the FDA recently amended its emergency use authorization to allow the treatment to be sold commercially.

“One of the things we’ve spent a lot of time thinking about in the last many months, and we’re going to continue this work, and you’ll hear more from the administration on this, is getting us out of that acute emergency phase where the U.S. government is buying the vaccines, buying the treatments, buying the diagnostic tests,” Dr. Ashish Jha, the White House’s top COVID-19 official, told an event hosted by the Chamber of Commerce Foundation earlier this month.

Healthcare industry officials say early formal talks are expected to begin this week with the Biden administration on the topic.

“We need to get out of that business over the long run,” Jha said.