Retiring Sen. Jeff Flake, R-Ariz., is considering a challenge to President Trump for the Republican nomination in 2020, he told reporters Friday.

“I’ve not ruled it out. I’ve not ruled it in. Just, somebody needs to run on the Republican side,” Flake said, according to Politico and The Hill.

Flake also pointed to Gov. John Kasich, R-Ohio, and Sen. Ben Sasse, R-Neb., as possible contenders. All three have been critical of the president. Kasich ran an unsuccessful presidential campaign in 2016.

Flake accused Trump of ruining the Republican Party’s long-term success with the way he conducted himself during the 2016 campaign and his two years as president.

“I hope somebody does [run], just to remind Republicans what it means to be conservative and what it means to be decent. We’ve got to bring that back,” Flake said. “You can whip up the base for a cycle or two but it wears thin. Anger and resentment are not a governing philosophy.”

Earlier Friday, Trump attacked Flake for trying to push legislation to protect special counsel Robert Mueller if Trump decides to fire him.

“Jeff Flake(y) doesn’t want to protect the Non-Senate confirmed Special Counsel, he wants to protect his future after being unelectable in Arizona for the ‘crime’ of doing a terrible job! A weak and ineffective guy!” Trump tweeted.

Trump also took credit on Wednesday for Flake’s decision to retire.

Flake said he expects suburban women and college-educated voters will be turned off by the Republican Party if Republicans who remain in Congress don’t stand up to the president.

Whether Trump can be re-elected in 2020 “depends on if one, there’s no alternative on the Republican side. And two, if the Democrats nominate someone on the far left, it’s possible,” the senator said.