Hi, Lee.
Consider what a "debt ceiling" is:
A self-appointed credit limit.
Imagine that you've maxed out your credit cards, your lines of credit, your equity line, tapped out your friends and relatives, wherein, they RUN to the other side of the street if they see you coming.
Now, you say ... "hmmm, perhaps I should raise my credit limits (debt ceiling), then I can make my minimum payments and take that long delayed vacation, maybe buy some new furniture and a new car. You don't have to contact your creditors to secure an additional line, you simply grant one to yourself! (hey, it works for me)
To take a simplistic view, that is what raising the "debt ceiling" truly is.
You mention that it's solely to "pay" for what has already been spent.
Actually, if you were in a similar situation, you would look to where you could cut spending, in order to pay down your debt.
Congress needs to simply cut spending, in order to pay debts already incurred (your "already spent" line).
Hey, it's not as if they lost their job and don't have revenues. Painful decisions need to be made.
Now, when we get to the point of unfunded liabilities (read "entititlements"), we be in some sorry hurt.
Time, long delayed, to get our house in order.