The administrator of a key US small business lending program to support companies devastated by coronavirus shutdowns said Thursday it has run out of funds due to massive demand.

The Small Business Administration, which was tasked with managing the $349 billion program, said on its website it was unable to accept new applications "based on available appropriations funding."

The statement comes as lawmakers in Congress argue over the next round of stimulus measures following an unprecedented series of emergency initiatives to prop up the US economy.

The government reported Thursday that another 5.2 million US workers filed for unemployment benefits, taking the four-week total to 22 million in a downturn that economists say presents the country with its most severe outlook since the Great Depression of the 1930s.

Other economic reports in recent days have shown plunging retail sales, lower manufacturing activity and a steep drop in homebuilding applications.

Congressional Republicans have pressed to immediately add $250 billion in funding for the program in a narrowly-tailored bill.

Democratic leaders have signaled support for the program, but want to include additional money for hospitals and local and state governments.

Negotiations involving Treasury Secretary Steven Mnuchin were ongoing, but as of midday Thursday there was still no agreement.

The initiative, the Paycheck Protection Program (PPP), provides loans to businesses with fewer than 500 employees to cover eight weeks of payroll or rent.

The loans convert to grants if restaurants, shops and other businesses maintain their employees or rehire laid-off workers by June 30.

The scale of the program, launched less than two weeks ago, has proved challenging to the SBA, a normally sleepy government agency whose lending operation is typically a fraction of the PPP's size.

"In less than 14 days, the SBA has processed more than 14 years of loans," SBA Administrator Jovita Carranza said Wednesday on Twitter as she called for more congressional funding.

An agency spokeswoman said late Wednesday that the agency has already committed more than $300 billion of the original allocation to support some 1.4 million applicants.

But the SBA has not released figures on how much of the funds have actually reached small businesses that are struggling to stay afloat.

There have also been questions about whether the money is reaching the neediest businesses and about the utility of the program to New York City and other coronavirus-ravaged regions where rehiring staff by the end of June may not be realistic.

Some prominent lenders, including JPMorgan Chase and Wells Fargo, said Thursday they would continue to process paperwork from small businesses in anticipation of additional funding from Washington.

"We know Congress is currently considering another round of funds soon," Jennifer Roberts, head of Chase Business Banking at JPMorgan, said in a statement.

"In the interim, we will continue to work our existing queue of applications so we can be ready."

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