U.S. Treasury Secretary Jacob Lew warned Congress the government will run out of money to pay its bills in mid-October.
That's unless lawmakers raise the country's borrowing limit, which is already capped at $16.7 trillion.
Lew said it's impossible for the Treasury Department to predict exactly when the debt ceiling will be reached.
He also warned that if the government doesn't take action soon, there won't be enough to cover Social Security payments, military salaries, Medicare, and other government programs.
The government spent more than it took in, running up annual deficits of more than $1 trillion per year for the past four years.
"It's not as if we get to go back and undo the commitments we made," Lew said. "These are old bills that have to be paid."
Republicans want to reduce deficits by cutting back on spending, while Democrats propose a mix of spending cuts and tax increases.