"As we saw two years ago, prolonged uncertainty over whether our nation will pay its bills in full and on time hurts our economy," Lew said in a statement. "Postponing a debt ceiling increase to the very last minute is exactly what our economy does not need a self-inflicted wound harming families and businesses."
In an interview with the Fox Business Network, Lew said that Oct. 17 was "a very real deadline" at which time Treasury will run out of the ability to borrow to run the government. Lew said after that "we will run down our cash very quickly."
Private economists said that Treasury's report did not overstate the potential fallout if Congress doesn't raise the current $16.7 trillion borrowing limit and the government defaults on its debt payments.
"There is no doubt in my mind that a default would be cataclysmic," said Mark Zandi, chief economist at Moody's Analytics. "It would cost us for generations to come because bond holders would require higher interest rates."