Treasury Secretary Steven Mnuchin participates in an interview during The Hill's Newsmaker Series 'Prospects for Tax Reform' at the Newseum April 26, 2017 in Washington, DC.

The Treasury will continue its suspension of issuing new debt for two more months, a measure intended to stave off default from hitting the federal borrowing limit, Treasury Secretary Steven Mnuchin wrote in a letter to Congressional leaders on Friday.

Mnuchin exhorted Congress to raise the federal borrowing limit before the new date.

"I believe that it is critical that Congress act to increase the nation's borrowing authority by September 29, 2017," Mnuchin wrote in the letter to Congressional leaders.

Mnuchin began employing measures to conserve cash in March, when U.S. debt hit the current statutory limit of nearly $20 trillion. The Treasury secretary said in his letter Friday that he would continue to withhold investments from the Civil Service Retirement and Disability Fund until Sept. 29.

Previously, the "debt issuance suspension period" was to end Friday, but Mnuchin extended the time frame. According to the Congressional Budget Office, the government may miss certain payments in October if the Treasury is no longer able to foot the government's bill.