Florida Gov. Charlie CristCharles (Charlie) Joseph CristWhite House: Pelosi calling Barr a liar 'beneath her office' Timeline: Barr, Mueller and the Trump probe Justice Department slams Pelosi for 'baseless attack' against Barr MORE's (R) Senate bid received the endorsement of Sen. John McCainJohn Sidney McCainPelosi receives John F. Kennedy Profile in Courage Award Romney: Trump 'has distanced himself from some of the best qualities of the human character' MSNBC host: Barr 'the most dangerous person' who works for Trump MORE (R-Ariz.) on Wednesday.

You may recall that Crist's well-timed endorsement of McCain in last year's GOP presidential primary boosted the Arizona senator to a win in the Florida primary. McCain went on to win the GOP nomination.

In a statement, McCain stressed Crist's fiscally conservative credentials.

"Now more than ever, we need leaders who are committed to lower taxes, limiting government spending, and fighting for the people are needed in Washington," McCain said.

"I was proud to have had Charlie's support in my campaign, and I am proud to support him in his campaign," McCain added.

Crist, whose popularity ratings remain high, is considered the GOP's best shot at holding retiring Sen. Mel Martinez's (R) seat next year. Crist is facing a primary, though, against former Florida House Speaker Marco Rubio (R).

A poll released on Tuesday showed Crist with a commanding 53 percent to 18 percent lead over Rubio.

The winner of the GOP Senate primary will face either Rep. Kendrick Meek (D) or state Sen. Dan Gelber (D) in the general election.

The poll also found Crist hold significant leads over both Meek and Gelber.