Treasury Secretary Jack Lew in a letter Friday to congressional leaders said that U.S. borrowing authority would likely not run past Feb. 27, calling on lawmakers to “move as quickly as possible” to raise the debt ceiling.

“Based on our best and most recent information ... we are not confident that the extraordinary measures will last beyond Thursday, Feb. 27," Lew wrote. "At that point, Treasury would be left with only the cash on hand and any incoming revenue to meet our country's commitments."

Republican lawmakers are working behind the scenes on a proposal to increase the nation's borrowing authority. GOP leaders have said they don't want another game of chicken over a possible default but have resisted calls for a so-called "clean" lifting of the debt ceiling.

Republicans have floated proposals that would undo changes to military retirement benefits, among other measures, in exchange for raising the debt limit.

The White House, however, has refused to compromise around the debt ceiling, saying failure to act would amount to a congressional dereliction of duty.

"Extraordinary measures are likely to be exhausted in less than three weeks," Lew wrote. "Congress is scheduled to be out of session for part of that time, and it would be a mistake to wait until the last possible minute to act."