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(CNN) —  

Republican Sen. Jeff Flake said he thinks President Donald Trump will and should have a Republican challenger in the 2020 presidential election.

“I do think the President will have a challenge from the Republican Party. I think there should be. I also think that there will be an independent challenge,” the Arizona senator said in an interview for David Axelrod’s show, “The Axe Files,” airing on CNN Saturday at 7 p.m. ET.

While he said it’s “not something I’m planning,” Flake did not rule out mounting a third party challenge to Trump, who announced his 2020 campaign manager earlier this week.

“I’ve not sworn off elected office in the future,” Flake said. “I think the fever will have to cool. There’s not much place for a Republican like me in a party like this right now.”

He argued that the “future may be coming” for a viable independent candidate.

“This polarization that you see on the right is also happening on the left,” Flake said. “And there has to be a huge swath of voters in the middle that are looking for something else.”

Flake, who announced last October he’s won’t seek reelection in the Senate, has strongly rebuked Trump and remained open to running for the White House in 2020.