Is Congress Violating the US Constitution By Playing Chicken With The Debt Limit?

I was wondering if Congress was somehow breaking the law, violating their oath of office that they take to uphold and defend the Constitution of the United States by not (or even suggesting to not) raise the debt ceiling. It turns out this is a murky and complex situation which the Constitution does and does not really address. 

We have to start this article with a couple of premises. First and most importantly I am fully aware that breaching the debt ceiling does not automatically put us into default with bond holders. Prioritization would be away for us to meet our legal obligations with bond holders without raising the debt limit. That raises more questions because prioritization, as Jared Bernstein points out is just default by a different name. Secondly I am making an assumption that the oath Congress takes at the beginning of their term legally binds them to uphold and defend the Constitution in all their actions. The last assumption I am making is threatening to not or actually failing to raise the debt ceiling amounts to questioning the validity of the contracts it enters with bond buyers when it goes to auction, which turns out to be a pretty important distinction. 

According to Section 4 of the 14th Amendment -  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. 

I am focusing on the validity of the public debt portion and the shall not be questioned portion. I think it is a reasonable assumption to assume contemplating defaulting on bond payments (see: Congressman Ted Yoho) could be interpreted by some as questioning the validity of a bond debt payment to an investor. 

I was wondering what the ramifications for not upholding their Constitutional obligations would be? Other parts of the Constitution are less vague and lay out Congress' responsibility in plain English. Congress is responsible for the paying bills. The first two powers the Constitution lists for Congress specifically that it collects taxes, pays bills and borrows money when necessary. Paying the bills could be interpreted by some as meeting legal obligations under the Social Security Act. Without raising the debt ceiling the Treasury does not have the cash on hand to both pay obligations and bond holders, forcing them to default on one payment or another.  Does the Constitution address this or is this an overlooked detail of federal Constitutional law? Or do I have no idea what I am talking about? I asked University of Pennsylvania Constitutional law professor Dr Kermit Roosevelt these questions. Dr. Roosevelt had this to say about Congress' constitutional responsibility. 
I’m not sure there’s anything in the Constitution directing Congress to raise the debt ceiling, unless you accept the argument that failing to do so amounts to questioning the public debt of the United States. Generally I think this is an unexplored area of constitutional law, since it (fortunately) hasn't come up much.
 The Constitution is clear on what could happen to the President for failing to act in accordance with his Constitutional duties.  Some have suggested President Obama could unilaterally raise the debt ceiling through executive order. A claim the President repeatedly reminds people he won't do and is Congress' responsibility. Failing to act on his part could be deemed as a dereliction of duty to uphold his Constitutional oath, potentially resulting in impeachment. This tends to be a damned if you do damned if you don't scenario as some members of Congress suggested invoking his rights under the 14th amendment would be in direct violation of the Constitution. I would ask the members of Congress who claim the President would be acting beyond his power under the 14th amendment that who is responsible for upholding the standing that America's debt go unquestioned as described in Section 4 of the 14th Amendment? Congress itself takes an oath at the beginning of each of their terms to uphold the Constitution as well. The Constitution is less clear as to what happens to Congress, assuming they share a responsibility to uphold the Constitution, specifically the 14th amendment Section 4. 

It seems though that we are not only headed for a potentially disastrous fiscal issue but a sort of Constitutional crisis as well. If and when the debt ceiling is breached someone, just not clear who, has violated the US Constitution and it might not be entirely clear who would be at fault or what their punishment is for doing so. 

This is my two cents on this whole debt ceiling debacle. Armando at the Daily Kos goes into much more detail on this and is worth a read.