There is a sufficient pad to deal with that opebo. The debt service is 6% of the budget. So 83% minus 6% leaves a 77% of the budget pad. Don't over stress yourself here.
You realize there is no fat at all there, don't you Torie? To put it into the Republican 'household budget' fantasy - the federal government is like a poor man whose rent, food, and debt payments are
just barely covered by his income. Reduce
your income by 6%, and I understand you would never notice it (which is a great argument for increasing your freeloading class's taxes, but I digress), but reduce a poor man's income by 6% and he starts missing payments, meals, and finally defaults/goes homeless. The Federal budget is at this level of tightness due to your class's robbery of the tax revenue.