I am not an economist but to pay the current monthly obligations or any monthly obligation when credit is available I can see one option.
With debt due in full plus interest and the monthly revenue the gov't takes in they need to cut expenses to cover the interest. Pay the full obligation plus interest with expense cutting to cover interest. Immediately sell new debt bonds or notes to cover the principle paid prior.
With the Gov't bailing out these financial institutions they could help in this matter.
Pay off, sell new bonds or notes, Debt limit not increased.
It will need to be a timely maneuver on the paying and reborrowing. Better make sure they have buyers for new bonds or notes.
Now they will need to get their budget in order on cutting here and there to operate with only revenue taken in and to pay down the principle.
They are not going to like cutting here and there. When in debt you work your way out of it.
I seen a headline this am where bondholders are going to be priority. Pay the bonds and reborrow.