Treasury Secretary Steven Mnuchin has called on Congress to raise the United States debt limit "at the first opportunity."

In a letter to congressional leaders dated Wednesday, Mnuchin said the Treasury will stop issuing certain state and local securities on March 15, when the most recent suspension of the debt limit expires. Mnuchin said the Treasury will likely start taking "extraordinary measures" the next day, when the U.S. will be at its statutory limit, to prevent default.

"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.