If McCarthy's deal falls through look for the 'Rats to try the 14th Amendment. They always get what they want - in this case crippling deficit spending.
I suspect that this DEFAULT on the debt is a lie. I think the #1 obligation of the treasury is to service the national debt.
You can do a search for federal mandatory spending and maybe servicing the debt will be mentioned. Cornell Law School sort of states my premise; look at this list of federal mandatory spending and after a wordy discussion of Social Security and Medicare and other various (questionable) mandatory spending obligations, at the very end is a brief paragraph:
Interest on the Debt
Although not officially a part of the mandatory budget, the interest on the national debt is also a mandated expense
So, what am I trying to say? Essentially, paying the mandatory interest on the debt - this year that will be close to a half of a trillion dollars - would mean cutting a myriad of pet projects involving give aways and pay offs without raising the debt ceiling.
I just seriously doubt that the US can default on its debt unless it refuses to obey the law. All this talk of default is just a way to fool the sheep by pulling on the ring in their nose - maybe.