The U.S. House of Representatives faces a politically tough vote on a measure that would raise the national debt ceiling by $1.9 trillion up to $14.3 trillion.
That would bring the total national debt to $46,000 for every person in the U.S.
Although the bill includes rules to try to restrain government spending, critics say Congress will be able to find ways around those rules.
Still, some in Congress won't vote to raise the national debt without the new restraints.
"We don't have a choice," Rep. John Tanner, D-Tenn., said. "We are on an unsustainable march toward a fiscal Armageddon."
But Moody's Investor Service warns that unless the U.S. economy grows more rapidly - or the government takes action to cut the deficit - America's top-level triple-A credit rating could come under pressure.