Congress needs to raise the nation's debt ceiling by Feb. 27 to avoid potential default on the country's obligations, Treasury Secretary Jack Lew warned in a letter to congressional leaders on Friday.

It comes as House Republicans are formulating their final plan on the debt limit, according to Politico — involving a "doc fix" on Medicare reimbursement rates and reinstituting some military benefit cuts. 

The House Republican plan would fix Medicare's Sustainable Growth Rate — the reimbursement rate for doctors who treat patients on Medicare — for nine months. The bill would pay for the fixes with another year of cuts to mandatory spending and changes in federal pension contributions, according to Politico.

A House GOP leadership aide told Business Insider he couldn't immediately confirm specifics of the plan.

As part of the bill to reopen the government in mid-October, the debt limit was suspended until Friday. The Treasury is now using so-called "extraordinary measures" point to keep borrowing and paying the nation's bills for a few weeks thereafter.

"Protecting the full faith and credit of the United States is the responsibility of Congress, because only Congress can extend the nation's borrowing authority. No Congress in our history hasfailed to meet that responsibility, and time is short," Lew wrote in the letter.

Here's the full letter from Lew:

See Also:

The One Brutal Quote That Sums Up John Boehner's Current Nightmare As SpeakerThe GOP's Two Main Options On The Debt Ceiling Just Blew UpThe GOP's Plan On The Debt Ceiling Would Actually Increase The Deficit