President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE criticized Sen. Joe Manchin Joseph (Joe) ManchinTrump meets with potential Supreme Court pick Amy Coney Barrett at White House Names to watch as Trump picks Ginsburg replacement on Supreme Court Momentum growing among Republicans for Supreme Court vote before Election Day MORE (D-W.Va.) on Thursday and encouraged voters to oust him in November, after cultivating a working relationship with the red-state Democrat last year.

Trump took particular aim at Manchin's decision to vote against legislation slashing tax rates in December, but added that he's "done other things I don't like."

"I’ll be honest with you, he does other things," Trump said at a tax reform roundtable event in White Sulphur Springs, W.Va.

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"So you’re going to have a chance to get a senator that’s going to vote our program," he added, referring to the upcoming election. "That’s going to help you in so many different ways. And you’re not getting that now."

Trump made the comments while flanked by two West Virginia Republicans looking to unseat Manchin — Rep. Evan Jenkins Evan Hollin JenkinsWest Virginia New Members 2019 Republican Carol Miller holds off Democrat in West Virginia House race Trump to fundraise for 3 Republicans running for open seats: report MORE and Attorney General Patrick Morrisey. The two men are running against each other in the Senate primary, along with former coal executive Don Blankenship.

Some Republicans have expressed concerns that Blankenship's fiery campaign could pose a threat to the GOP's chances of winning the seat. He presided over the Upper Big Branch Mine, where an explosion killed dozens of miners eight years ago, but has still posted strong polling numbers in the GOP primary.

Trump beat out Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE by a wide margin in West Virginia in 2016, making Manchin a vulnerable target for Republican challengers in the 2018 midterms.

Manchin fired back at comments from the event on Thursday, calling it "political posturing" and saying that "West Virginians deserve answers" on various issues, such as rural hospitals potentially going bankrupt and why tax cuts for the middle-class are not permanent.

"What will the 200,000 West Virginians do when they lose healthcare coverage?" Manchin asked, while not directly mentioning Trump. "How much will Republicans cut from Medicare and Social Security?"

The West Virginia Democrat has been notably friendlier with Trump than many of his Democratic colleagues. In December, he tweeted – and later deleted – a photo of himself giving a thumbs-up alongside Trump at the White House. In January, he and another centrist Democrat were invited to an exclusive meeting with Trump after the government shutdown.

Still, Manchin joined Senate Democrats in December in voting against the GOP tax bill, which he criticized as a “political tool” pushed without bipartisan consensus that hurts seniors and those who obtain health care from the open market.

Manchin's relationship with the Trump administration had definitively soured by earlier this year, when Manchin exchanged testy words with Vice President Pence over how seriously the White House means it when it touts "bipartisanship."

Updated: 6:45 p.m.