It’s hard to imagine a better metaphor for Donald Trump’s presidency than if, backed by a Republican-controlled Congress, he celebrates his 100th day in office by shutting down his own government. This outcome is by no means inevitable, but the odds of it are astonishingly high: Government funding expires Friday, and Trump hits the 100-day mark on Saturday.

It is unprecedented in the modern era for an appropriations fight to end in a government shutdown when one party has full control—or really under any configuration other than when the president is a Democrat and Republicans control at least one chamber in Congress. The current partisan alignment should effectively preclude a shutdown, but Trump’s particular mix of incompetence, narcissism, and poor judgment is potent enough to confound basic game theory. As in so many realms of public affairs, Trump’s mere presence creates massive amounts of uncertainty.

To see how Trump changes the normal calculation, consider what the appropriations process would look like in a more generic case, where Republicans enjoyed identical congressional majorities but under a president who behaved rationally.





In that case, we would expect the president and GOP leaders to work backwards from a desire to avoid a shutdown, toward an optimal outcome in which appropriations did not lapse and Congress funded as many of their priorities as possible. The hard fact that funding the government almost always requires a measure of bipartisanship places a fairly firm limit on what’s possible in that context. The minority party has a disproportionate amount of power over annual appropriations, but you go to the spending fight with the army you have, not the army you might want, or wish to have at a later time. If Democrats were horribly recalcitrant, they could reject every single Republican bid, leaving Republicans a choice between simply extending existing funds or shutting down the government—in which case a rational party would harrumph and agree to extend the funds.

The fact that Democrats are not horribly recalcitrant creates room for limited dealmaking. Republicans want to spend more money on defense and immigration enforcement, Democrats want to fund other priorities, and to the extent that these different points of emphasis don’t cross any ideological redlines, the parties can accommodate one another. But Democrats won’t persuade Republicans to agree to adequately fund the IRS, just as Republicans won’t convince Democrats to help them gut the EPA. The construction of a wall along the southern border, meanwhile, is a non-starter for Democrats and many Republicans. A rational GOP president would accept this reality and move on. Trump has made its inclusion in the funding bill a top priority.