The nitty-gritty of the law puts caps on the amount that Congress can spend on defense and on nondefense discretionary programs up through 2021. It bars Congress from shifting money from defense to nondefense programs, or back again, under the cuts. And congressional rules prevent legislators from using reconciliation—a way to vault over the 60-vote threshold in the Senate—to get out from under the caps or to eliminate them entirely.

In other words, to spend more than the Budget Control Act allows, the party in power needs to pass a law with support from the other side.

Trump has proposed eliminating the defense sequestration cap, and his budget seems to suggest setting a single defense and nondefense cap. “My understanding of what the White House is actually proposing is to replace the separate caps on defense and nondefense spending with one cap on total discretionary spending,” Ed Lorenzen, a budget expert at the Committee for a Responsible Federal Budget, told me. But to do so would require Democratic votes.

Those votes are unlikely to be forthcoming—certainly not if Trump or Republicans in Congress are pushing for austerity for diplomatic programs and killing Big Bird. Democratic aides said that they would be demanding dollar-for-dollar parity, meaning an extra dollar for domestic programs for every extra dollar in defense, as a bare minimum. “As has been shown over and over again the past few years, Republicans cannot complete the appropriations process on their own under sequestration’s unrealistic targets,” Steny Hoyer, the House minority whip, said in a statement last month. “President Trump will soon learn that funding federal agencies is much easier with bipartisan cooperation.”

There might, however, be creative ways out of this budgetary bind. The White House could put its defense appropriations in the Overseas Contingency Operations fund, meant for war spending, Harrison theorized. But the skinny budget itself does not use that budgetary maneuver, and Trump’s own budget director, Mick Mulvaney, has been among the harshest critics of politicians putting normal defense outlays into the OCO and using it as a “slush fund.” (The White House did not respond to questions about how it plans to negotiate sequestration.)

Trump could get more creative, prompting congressional Republicans to break parliamentary rules to pass his budget, Stan Collender, a budget expert and executive vice president at Qorvis MSLGROUP, told me. But that seems unlikely as well. “You’d have to bastardize the reconciliation process,” Collender said. “It would require the parliamentarian being bought and paid for, or replacing him, or unanimous consent. And there isn’t unanimous consent for a reading of the Lord’s Prayer in Congress right now.”

Or Trump could demand that Congress pass a budget in defiance of the sequestration caps, with the White House spending money in defiance of federal law. “We’re talking about the president violating federal law, the budget office violating federal law, and the Senate majority leader flouting federal law,” Collender told me. “Trump’s base would probably enjoy that a lot. But we’re talking about lawlessness, or legislative chaos. The last time that happened with the budget was with Nixon and impoundment.”