read the active legislation in the US Congress.
apparently there is some kind of legal limit to the amount of debt the feds can spend. if they run out, then can pass a law to raise the limit.
"Final version (Enrolled Bill) as passed by both Houses.
One Hundred Tenth Congress of the United States of America Begun and held at the City of Washington on Thursday, the fourth day of January, two thousand and seven
Increasing the statutory limit on the public debt.
Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That subsection (b) of section 3101 of title 31, United States Code, is amended by striking out the dollar limitation contained in such subsection and inserting in lieu thereof $9,815,000,000,000.
Speaker of the House of Representatives. Vice President of the United States and President of the Senate. "
the previous version of Title 31 Section 3101 from Jan 2, 2006 says: "(b) The face amount of obligations issued under this chapter and the face amount of obligations whose principal and interest are guaranteed by the United States Government (except guaranteed obligations held by the Secretary of the Treasury) may not be more than $8,184,000,000,000, outstanding at one time, subject to changes periodically made in that amount as provided by law through the congressional budget process described in Rule XLIX  of the Rules of the House of Representatives or otherwise."
Congress is spending more money than it is given. I dare say it is beyond their mandate, or it should be. Debt spending creates inflation which robs from us all.