One question I hear people debating today is whether or not these agreed-upon spending caps will preempt a government shutdown fight when the current continuing resolution expires at the end of September. The correct answer is “no,” it will not. Even if you grant that agreement on caps preempts disagreeing about the level of domestic discretionary spending, that doesn’t take away the possibility of a huge fight over policy riders. You remember policy riders, don’t you? Provisions like defunding NPR, ensuring that nobody who receives taxpayer dollars ever shakes hands with anyone who’s ever performed an abortion, etc. Especially under a scenario where party leaders aren’t disagreeing about the total quantity of spending, the field will be wide open for debates over policy riders.
Beyond that, you have to consider that lots of people aren’t party to this deal. In particular, if it passes, it will pass with many Republicans voting “no” and some Democrats voting “yes.” But when it comes time to write appropriations bills, House Republicans are going to return to cartel behavior and seek to write legislation that unites rather than divides their caucus. That means a bill that’s agreed to be plenty of conservative Republicans who reject the debt ceiling agreement. That means some combination of even deeper spending cuts and tempting conservative policy riders. Then a bill like that won’t be able to get through the Senate, so we’ll be at risk of an appropriations lapse and a government shutdown. Then we’ll need to negotiate something new.