When the president hits the stage Thursday in Great Falls, Montana, it likely won’t be your average Donald Trump political rally. This one’s personal.

That’s because Trump is heading to Big Sky Country to do more than just gin up Republican voters and try to take away a Democratic Senate seat in a traditionally red state. He has a personal score to settle with the state’s senior senator, Democrat Jon Tester, whom he has called “very dishonest.”

Why? Three words explain it: Doctor Ronny Jackson.

Trump and many senior White House officials still hold a grudge against Tester over the failed nomination of the Navy rear admiral and former Trump military physician to become secretary of the Department of Veterans Affairs. Tester made public allegations about questionable management and conduct from whistleblowers against Jackson that helped him decide to step aside.

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After Jackson withdrew his name from consideration, Trump and his aides accused Tester of pushing false allegations, even saying he should no longer be a senator.

A senior White House official on Wednesday did not discount the notion that Thursday’s event is personal for Trump, who quickly came to think highly of Jackson and called Tester’s allegations “phony.”

“The Secret Service is unable to confirm (in fact they deny) any of the phony Democrat charges which have absolutely devastated the wonderful Jackson family,” the president tweeted on April 28, adding this broadside: “Tester should resign.”

Allegations made by Senator Jon Tester against Admiral/Doctor Ron Jackson are proving false. The Secret Service is unable to confirm (in fact they deny) any of the phony Democrat charges which have absolutely devastated the wonderful Jackson family. Tester should resign. The…..

— Donald J. Trump (@realDonaldTrump) April 28, 2018

Senate Veterans Affairs Chairman Chairman Johnny Isakson, R-Ga., backed Tester’s actions. The Defense Department’s inspector general has opened a probe of Jackson’s behavior.

The social media post did not lead Tester to decide to step down over the Jackson situation, so Trump is traveling there to try to get Tester out of the Senate the old fashioned way: By beating him at the polls.

And Trump and Republicans have a legitimate shot at doing that. Inside Elections with Nathan L. Gonzales puts his race against state Auditor Matt Rosendale in the Tilts Democratic column. A recent Gravis poll gives Tester an 8 point lead; he won in 2012 by nearly 4 percentage points.

While Trump is likely to throw ample rhetorical haymakers at the Democratic senator, their relationship is, as often is the case with the former reality show star and real estate mogul, more complicated.

Montana Democrats this week released a digital ad pointing out Trump has signed 16 bills into law of which Tester was a major proponent. The ad notes Trump said it was a “great honor” to sign one veterans bill and that he was “proud” to make another law.

And Tester’s re-election campaign bought a full-page ad in the Great Falls Tribune and ran similar ads in 13 other Treasure State newspapers that strike the same tone.

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“Welcome to Montana, and thank you President Trump for supporting Jon’s legislation to help veterans and first responders, hold the VA accountable, and get rid of waste, fraud and abuse in the federal government,” that ad in the Tribune states. “Washington’s a mess — but that’s not stopping Jon from getting things done for Montana.”

The campaign said it was also planning a statewide radio ad buy.

Trump is likely to repeat his assessment of Tester from another April 28 tweet in which he dubbed the senator “Very dishonest and sick!” over the Jackson nomination, adding, “Tester should lose race in Montana.”

Secret Service has just informed me that Senator Jon Tester’s statements on Admiral Jackson are not true. There were no such findings. A horrible thing that we in D.C. must live with, just like phony Russian Collusion. Tester should lose race in Montana. Very dishonest and sick!

— Donald J. Trump (@realDonaldTrump) April 28, 2018

But Tester is playing it cool ahead of the rally, a reflection of the state’s traditional Republican bent and Trump’s 20.5 percentage point win over Hillary Clinton in the 2016 election.

“I’ll continue to work with anyone from any party to get things done for Montana,” he said in a statement released by his campaign. “President Trump, I’ll clear my schedule for whenever you are ready to sit down and talk about how we can get to work for Big Sky Country.”