The lack of money could force the agency to essentially start operating on IOUs if Congress doesn't act in time.
As of Tuesday morning, FEMA'S Disaster Relief Fund had just $1.01 billion left. Of that, $541 million was "immediately available" for response and recovery efforts related to Hurricane Harvey, according to a spokeswoman.
An official with Office of Management and Budget told CNN Thursday that the latest estimate shows that FEMA has enough to get through Saturday. When asked how much money remains in the FEMA disaster relief fund as of Thursday the official said, "it's hard to say at this point as this not like traditional spending."
The House passed an emergency relief bill Wednesday
that would provide $7.85 billion in emergency funds -- the vast majority of which to FEMA, with some going to the Small Business Administration.
The Senate is expected to vote on that bill Thursday, tacking on another $7.4 billion in emergency funds for a total of $15.25 billion for FEMA's disaster relief fund.
On top of that, the Senate is voting on another $6.7 billion for funds that were already slated to go to FEMA in a spending bill that keeps the government open for another three months.
Once the bill goes back to the House -- so it can vote on additions made in the Senate -- Congress will have voted on close to $22 billion in funds for disaster relief.
But if for some reason the agency does run out of money before Congress acts, the lights aren't expected to go out.
The head of FEMA, Brock Long, said he'll keep "pushing forward" no matter what happens in Congress. "I'm not letting money get in the way of my operation," he told CNN's Wolf Blitzer on "The Situation Room."
Thursday morning, also on CNN, Long added that he'll "never allow paper work and money to get in the way of saving lives."
Craig Fugate, the former administrator of FEMA under President Barack Obama, told CNN that when the agency ran out of money during Hurricane Irene in 2011, it continued to work at full speed, essentially breaking a law called the Antideficiency Act, which prohibits an agency from spending or obligating money that isn't available or hasn't been authorized.