The Treasury Department is taking measures to buy time until the end of February. They include: suspending some investments in benefit funds for federal workers.
But after that, the Treasury will not be able to pay all of the country's bills in full and on time.
Congress must vote to raise the debt ceiling, setting the stage for another fight on Capitol Hill.
Some Republican lawmakers view the debt limit as leverage in negotiations with President Obama over spending cuts and reforms to Medicare and Social Security.