Treasury Secretary Steve Mnuchin is urging Congress to raise the U.S. debt ceiling “at the first opportunity.”

In a letter to House Speaker Paul Ryan, Mnuchin pointed out that the suspension of the statutory debt limit will expire on Wednesday, March 15, 2017. The following day, the outstanding debt of the United States will be at the statutory debt limit.

At that point, the Treasury will begin to take “extraordinary measures” to prevent the U.S. from defaulting on its debt, Mnuchin wrote in the letter dated March 8.

“As I said in my confirmation hearing, honoring the full faith and credit of our outstanding debt is a critical commitment. I encourage Congress to raise the debt limit at the first opportunity so that we can proceed with our joint priorities,” Mnuchin wrote.

Mnuchin said that the Treasury will begin by suspending the issuance of certain special purpose Treasury securities to state and local governments.

The debt ceiling is statutory limit set by Congress on the total amount that the U.S. Treasury can borrow. It is currently set at $20.1 trillion but was suspended in late 2015. At the end of the fourth quarter of 2016, the debt of the U.S. government had reached nearly $20 trillion. Mnuchin’s letter makes it clear that we will have reached the limit when the current suspension expires next week.

The debt of the U.S. government has more than doubled from the $9.2 trillion owed at the end of 2007. It began rising rapidly with the onset of the Great Recession and financial crisis.