President Trump on Wednesday rehashed grievances with Sen. Jon Tester, D-Mont., over how he torpedoed Trump's first choice for secretary of the Department of Veterans Affairs.

"Ever since his vicious and totally false statements about Admiral Ron Jackson, the highly respected White House Doctor for Obama, Bush & me, Senator John [sic] Tester looks to be in big trouble in the Great State of Montana! He behaved worse than the Democrat Mob did with Justice K!" Trump tweeted, referring to the protests against Supreme Court Justice Brett Kavanaugh's nomination.

Former White House physician Rear Adm. Ronny Jackson withdrew his candidacy as Veterans Affairs secretary following unsubstantiated reports of him being drunk on the job, over-prescribing pain medication, and creating a hostile work environment. Tester, the top Democrat on the Senate Veterans Affairs' Committee, shared some of the allegations with members of the media.

Tester is among the vulnerable Democratic senators up for re-election in states Trump won handily in 2016. The lawmaker, who is vying for his third term in office, is 3 percentage points ahead of Republican opponent Matt Rosendale, according to RealClearPolitics' poll aggregator.

Trump is holding a rally in Missoula, Mont., Thursday, and is expected to tout Rosendale as the right candidate for Montana. The president has previously called on Tester to resign over his handling of the Jackson controversy.