Chris O'Meara/ASSOCIATED PRESS Donald Trump has won some Republican endorsements. But now, a Republican Senator is urging people to hold off.

Sen. Jeff Flake (R-Ariz.) encouraged his colleagues on Sunday to withhold their endorsements of Donald Trump as a means of maintaining leverage over the presumptive Republican nominee.

Appearing on CBS’ "Face the Nation," Flake said he was horrified by recent statements from Trump and that he lacked confidence that the real estate tycoon would “turn the corner” in terms of his temperament.

In order to facilitate that change, Flake suggested that his fellow Republican senators simply not offer their support -- a fairly remarkable bit of subterfuge directed at their own party’s presidential candidate.

"So I hope that a number of us at least will withhold endorsement, I've not endorsed, until we see,” said Flake, according to a transcript provided by the show. “It's not a comfortable position to not support your nominee of the party. None of us want to be in this position. But there are certain things that you can't do as a candidate. And some of the things he's done, I think, are beyond the pale."

Trump had managed to make some inroads with Republican leadership after securing the nomination, with House Speaker Paul Ryan (Wis.) and Senate Majority Leader Mitch McConnell (Ky.) reluctantly backing his candidacy despite the obvious pains it caused them. But Trump's recent time on the trail, during which he claimed an American judge with Mexican heritage couldn’t objectively try a case involving him, caused a number of other Republican lawmakers to back away. One, Sen. Mark Kirk (R-Ill.,) retracted his endorsement. And now Flake is encouraging the fence-sitters to hold tight.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.