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.