Debt Ceiling - Unconstitutional?

According to a piece on Olbermann tonight,  there are Democrats who believe this to be the case and are considering a challenge to the debt ceiling law as violation of the 14th amendment, requiring that the US make good on all of our debts.   "The validity of the public debt of the United States, authorized by law... shall not be questioned," reads the 14th Amendment.   This link will take you to the full article in the Huffington Post.