Washington (CNN) Sen. Jeff Flake hit back at President Donald Trump over what the Arizona Republican said is a misrepresentation of his support for GOP Rep. Martha McSally's Senate bid.

The President took to Twitter to offer his congratulations on McSally's projected Tuesday night primary victory -- and took a swipe at Flake, a vociferous Trump critic who is retiring from the Senate, in doing so.

"Martha McSally, running in the Arizona Primary for U.S. Senate, was endorsed by rejected Senator Jeff Flake....and turned it down - a first! Now Martha, a great U.S. Military fighter jet pilot and highly respected member of Congress, WINS BIG. Congratulations, and on to November!," Trump tweeted in the early hours of Wednesday.

CNN has reached out to the McSally campaign for comment. Flake disputed Trump's claim early Wednesday morning.

"Sorry, @realDonaldTrump. I made no endorsement in this race. I think the last endorsement I made was in the Alabama race," the Arizona Republican tweeted with a picture of the $100 check he gave to Democratic Sen. Doug Jones' special election campaign in December 2017. Jones upset the Trump-backed Roy Moore in that race, a Republican who was accused of sexual abuse.

Sorry, @realDonaldTrump. I made no endorsement in this race. I think the last endorsement I made was in the Alabama race.https://t.co/yob5VVNAOe pic.twitter.com/KbzKAGRdDB — Jeff Flake (@JeffFlake) August 29, 2018

Flake, who announced in October 2017 he would not seek re-election, did not formally endorse any of the candidates running to be his successor.

"Nobody would be asking for it in the Republican primary, I can tell you that. It -- this is very much, and you know I'm not happy about it, but this is the President's party right now," Flake said on NBC's "Meet the Press" Sunday, alluding to his notoriously contentious relationship with Trump.

However, Flake did offer words of support for McSally on Tuesday.

"I think McSally will win. I hope she does. That's the only shot that obviously Republicans have to hold on to the seat," he told reporters on Capitol Hill Tuesday morning.

McSally defeated two hardline conservative candidates: former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio in Tuesday's primary election. She will face Democratic Rep. Kyrsten Sinema in November.