Donald Trump is firing back at "overrated" conservative columnist George Will, days after the Washington Post writer said he left the Republican Party because of its presumptive GOP nominee.

Trump tweeted out his attack of Will early Sunday, saying the Pulitzer Prize-winning commentator had "lost his way long ago":

George Will, one of the most overrated political pundits (who lost his way long ago), has left the Republican Party.He's made many bad calls — Donald J. Trump (@realDonaldTrump) June 26, 2016

Will, also a Fox News contributor, told right-leaning PJ Media on Friday that he had become an "unaffiliated voter" in Maryland because of Trump's influence on the GOP. He urged Republicans to "make sure he loses" and that the better option would be to "grit their teeth for four years" of Hillary Clinton before being able to take back the White House.

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Will has long been critical of Trump, saying the billionaire was a "counterfeit Republican" who did not adhere to true conservative principles.

Back in April, Will warned that Trump's "damage to the Republican Party, although already extensive, has barely begun."

It is unclear what "bad calls" Trump was referring to when trashing Will.