Sen. Jeff Flake said on Sunday that it's "becoming increasingly difficult" to imagine Donald Trump making the changes he would need to earn the Arizona Republican's endorsement.
Specifically, Flake said that Trump will need to change both his position on things like immigration reform, partnerships with NATO and the ban on Muslims as well as his "tone and tenor," pointing to remarks the GOP nominee has made about Mexicans being rapists that do not go over well in Arizona.
"I still hope to support our nominee, [but] it's becoming increasingly difficult to see him making the changes he needs to change," Flake said on "Face the Nation."
Flake said he met with Trump's running mate, Indiana Gov. Mike Pence, whom he called a "good guy" who he hopes can influence the GOP nominee.
"His pitch was that Donald Trump is a different guy in private than he is in public," Flake said. "If you could govern in private, I guess it would be ok, but you can't."
Flake said some of the things that are particularly troubling are Trump's comments on Hispanics, especially earlier this year when Trump suggested a Hispanic judge couldn't do his job effectively because of his race.
"You can't expect to win Arizona when you make statements like that," Flake said.
He also said Trump will need to come up with a more serious immigration reform plan if he hopes to appeal to Arizona voters.
"You can't just throw platitudes out there about a wall or Mexico paying for it and be taken seriously here," Flake said.