The relevant portion of the fourteenth amendment is section 4, which states:
Section. 4. 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 argument against Obama here is that this portion of the Constitution speaks to incurred debt, not future debt. Nonetheless, Tea Party freshmen like Rep. Tim Scott (R-SC) are already on record as saying such a move would be impeachable.
First up, here is Carney saying, 'we have to take action to ensure we do not default.'
Here is none other than Muslim Rep. Keith Ellison (D-MN) arguing in support of Obama invoking the fourteenth:
He's not the only one. Senator Bernie Sanders (Socialist - VT) says Obama should do that as well:
Here is Rep. Scott at a recent town hall:
h/t Weasel Zippers