"We were just informed last night (that) the National Nuclear Security Administration (NNSA) -- the group that handles and manages our nuclear stockpile -- that the carryover funding they've been using is about to run out," Republican Congressman Mike Rogers told reporters.

"They will have to lay off 80 percent of their employees."

The federal government shutdown is set to head into a new week with no end in sight after the Senate failed for a 10th time on Thursday to pass the Republican bill to reopen the government.

It was not clear if Rogers was referring to temporary enforced leave during the shutdown, or permanent layoffs.

But he added: "These are not employees that you want to go home. They're managing and handling a very important strategic asset for us. They need to be at work and being paid."

The United States has a stockpile of 5,177 nuclear warheads, with about 1,770 deployed, according to the global security nonprofit Bulletin of the Atomic Scientists.

The NNSA is responsible for designing, manufacturing, servicing and securing the weapons. It has fewer than 2,000 federal employees who oversee some 60,000 contractors.

Energy Secretary Chris Wright told USA Today in an interview Thursday about the effects of the shutdown on the NNSA that "starting next week, we're going to have to let go tens of thousands ... of workers that are critical to our national security."

The daily paper reported that staff at the agency had been told that furloughs -- or enforced leave without pay -- could begin as soon as Friday, citing unnamed employees.