Some on the far left are urging Obama to disregard his own debt ceiling deal in favor of using the "nuclear option" to unilaterally raise the debt limit. This argument, raised by a number of House Democrats, relies upon a weak interpretation of the fourteenth amendment, which states:
The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned. But neither the United States nor any State shall assume or pay any debt or obligation incurred in aid of insurrection or rebellion against the United States, or any claim for the loss or emancipation of any slave; but all such debts, obligations and claims shall be held illegal and void.
The claim seizes upon the lines "[t]he validity of the public debt of the United States... shall not be questioned" dubiously asserting that this signifies the constitution allows the president to unilaterally issue debt. However, the argument is so full of holes that even the administration has categorically rejected it. Obama stated, “I have talked to my lawyers... They are not persuaded that that is a winning argument.”
The truth is that this part of fourteenth amendment, which was written in the midst of the Civil War, was drawn up to prevent Congress or the president from repudiating existing debts. This was rooted in the fear that after reunification with the South, former Confederate legislators would try to wipe out Union debt. Its aim was to ensure that a congress could not backtrack on the promises of previous congresses, undoing commitments made to debtors and thus injuring the debtors and the United States. The amendment in no way authorized the president to unconditionally incur new debt and certainly did not question the primacy of Congress’s responsibility to issue debt or the constitutionality of a debt limit. Stanford's Michael McConnell sums up the constitutional law nicely.
Section Four of the Fourteenth Amendment does not create a back-door method for the Administration to borrow more money without congressional authorization. For Congress to limit the amount of the debt does not “question” the “validity” of the debt that has been “authorized by law.” At most, it means that paying the public debts and pension obligations of the United States, as they become due, has priority over all other spending.
The leftist perspective is merely an attempt to twist the constitution to prevent needed fiscal reforms. Not only is it unconstitutional for Congress to abdicate this responsibility - Article 1, Section 8 of the Constitution says that only "[t]he Congress shall have Power... To borrow Money on the credit of the United States" - but, as argued elsewhere, such an interpretation would place the United States in dire straits, removing a huge check on rampant expenditure.