There's enough money coming into the Treasury to service the payments on the current debt. But if you don't borrow more money you have to shut down vast amounts of federal outlays. And the most logical places to start are with Social Security payments and Medicare reimbursements. Stuff like cutting Social Security checks in half starting the following week.
You see, these were trust funds, and the Government had a fiduciary duty to repay them, before Congress purloined them all and left IOUs, which get paid from current revenue and borrowing. In contrast the Departments of Agriculture, Energy, Education, FCC, etc have no such IOUs, so why not close them down, in fact close down everything south of the Mason Dixon and north of the Rappahannock River!
This seems to be the mindset of the left, void fiduciary duties and keep on trucking to the end of the earth!