President Trump, as Washington frets over the partial government shutdown looming on Sunday, is urging House Republicans to let the clock strike midnight. His aim, though, is not so much using the fight as an opportunity to rein in spending but rather to cut money for the federal investigations against him.

His position, however solipsistic, could make a resolution that much more difficult to reach. Calling September 30 “a very important deadline” in a Telegram post, Mr. Trump said, “Republicans in Congress can and must defund all aspects of Crooked Joe Biden’s weaponized government that refuses to close the border and treats half the country as enemies of the state.”

So far, this is in line with House conservatives who are blocking a deal. They’re concerned about the deficit ballooning from President Biden’s spending and how it’s led to a 40-year-high in inflation. Their solution is for Speaker McCarthy to use the House, where all spending originates, to turn off the spigot and shrink the size of government.

Mr. Trump, however, didn’t stop on policy. Moving on to the personal, he described the shutdown showdown as “the last chance to defund these political prosecutions against me and other patriots.” House Republicans, he said, “failed on the debt limit, but they must not fail now. Use the power of the purse and defend the country.”

This call for a lifeline looms large because of Mr. Trump’s dominant position in the GOP. He holds a commanding lead in polls for the Republican nomination — a Daily Mail survey found that voters considered him the winner of Wednesday’s debate even though he didn’t attend — and is tied or ahead of Mr. Biden in their expected rematch next fall.

A Washington Post-ABC poll last week showed Mr. Trump with a whopping 10-point lead over Mr. Biden. While the paper called the results an “outlier,” Republicans, like Speaker McCarthy, who want to deal know they’re clinging to a narrow majority and are unwilling to buck their party’s Big Dog.

“A shutdown would only give strength to the Democrats,” Mr. McCarthy told Fox News last week. “It would give the power to Biden. It wouldn’t pay our troops. It wouldn’t pay our border agents; more people would be coming across. I actually want to achieve something.”

His challenge is that Mr. Trump wants to achieve something, too, and the two somethings are at odds with Republicans who want to avoid a shutdown such as Mr. McCarthy’s opposite number in the Senate, the minority leader, Mitch McConnell, rendering the senator’s endorsement of a “standard, short-term continuing resolution” dead on arrival.

“In order for work on appropriations to continue uninterrupted,” Mr. McConnell said Tuesday on the Senate floor, “Congress needs to extend government funding by the end of this week. The sooner Congress keeps the light on, the sooner these important conversations can resume.”

Mr. McConnell said that “the clearest path forward is this standard, short-term continuing resolution. Our work this week needs to produce the resources and flexibility to maintain the central government functions at their current rates of operation while progress on full-year appropriations continues.”

None of this aligns with Mr. Trump’s goal to make the shutdown about his future. It also doesn’t help the case of Mr. McConnell’s wing that funding for services deemed essential — including Social Security checks, funding for Ukraine’s government, as well as Capitol Hill’s electric bill — will be unaffected if the partial shutdown takes effect.

Demonstrating the ire that will be rained down on Republicans who oppose a shutdown, Mr. Trump wrote on Truth Social, “It’s time Republicans learned how to fight! Are you listening, Mitch McConnell — the weakest, dumbest, and most conflicted ‘Leader’ in U.S. Senate history?”

Government shutdowns have become theater for Washington in recent years, unlike the eight under President Reagan which passed without much notice by the public. By adding his own political drama into the script, Mr. Trump is hoping to use his influence to write a more favorable ending to his legal troubles, happy to have the clock strike midnight if it means he can see some daylight at the end of the justice department’s prosecutions against him.