Former Texas Gov. Rick Perry is keeping up a public feud with GOP presidential rival Donald Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE, saying Monday that the businessman is becoming a "cancer" to conservatism.

"Defending conservatism against the cancer of Trump-ism – I hope you’ll join me Wednesday in DC," Perry tweeted Monday, linking to a policy forum in Washington where he will speak later this week.

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Perry said last week that "Trump-ism" involves "a toxic mix of demagoguery and nonsense," after which Trump said Perry "should be forced to take an IQ test" before the first GOP debate.

The pair have sparred for weeks after Perry become one of the first GOP presidential candidates on July 2 to denounce Trump's controversial remarks on immigrants from Mexico.

That led to a series of back-and-forth criticism between the two. Amid the feuding, Trump has skyrocketed in presidential polls, while Perry has fought to solidify a position in next month’s GOP debate.

Their clash saw an added element over the weekend, when Perry said that Trump disqualified himself for president when he suggested Sen. John McCain John Sidney McCainMomentum growing among Republicans for Supreme Court vote before Election Day McConnell urges GOP senators to 'keep your powder dry' on Supreme Court vacancy McSally says current Senate should vote on Trump nominee MORE (R-Ariz.), a former prisoner of war during Vietnam, was not a hero and that he preferred those who did not get captured.

Trump's criticism of McCain drew rapid backlash from other Republicans over the weekend.

Perry, who served in the Air Force, added Sunday on NBC's "Meet the Press" that Trump's comment was "a bullet that went through John McCain and hit a lot of us that were in the uniform in this country."

The former Texas governor continued to pan Trump's "absurdity" on Monday in an op-ed for National Review, writing that the position of president "is serious business, not a reality TV show."