Former Sen. Jeff Flake, R-Ariz., announced Tuesday morning that he will not challenge President Trump in a 2020 Republican primary.

Speaking on CBS – where he has signed on as a contributor – Flake said that he still believes that some Republican needs to challenge Trump in the primaries, but that it won’t be him.

“I have always said that I do hope that there is a Republican who challenges the president in the primary. I still hope that somebody does, but that somebody won't be me. I will not be a candidate,” Flake said on “CBS This Morning.”

During his last two years in the Senate, Flake became one of the most vocal critics of Trump within his own party and there were widespread rumors that he would mount a primary challenge to the president for the Republican nomination. Flake himself fueled those rumors in November by saying he had “not ruled it out.”

But on Tuesday Flake said that it will be an uphill battle for any Republican trying to challenge Trump.

FLAKE SLAMS GOP, SAYS HE FEELS LIKE HE DOESN'T BELONG TO ANY POLITICAL PARTY

“It’s a difficult path anyway. The [Republican National Committee] and the president’s campaign are now melded, they’re trying to do everything they can to squelch any opposition," Flake said. "I still hope that some, and some are still talking about it, do run, I think that that’s healthy and I’m not a fan of this president. But that won’t be me,”

Despite supporting numerous policies of the Trump administration, Flake had a combative relationship with the president that dated back to the 2016 presidential campaign when Flake lambasted Trump for his criticism of Sen. John McCain.

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Flake has hinted that he believes someone like Sen. Ben Sasse, R-Neb., or former Ohio Gov. John Kasich should challenge Trump in a Republican primary.

Kasich, a moderate Republican who has run for president twice already and is another vocal critic of the president, said in November that he was “very seriously” considering another White House bid.