DeSantis, who was endorsed by Trump, beat state Agriculture Commissioner Adam Putnam for the Republican nomination for governor, the Associated Press projected. With more than one-third of the vote counted.
Rick Scott is vacating the governor's mansion to run for Senate.
DeSantis entered the race in January and largely built his name recognition with near-nightly Fox News appearances.
The victor of the Florida governor's race will give his or her party an advantage in a key political battleground heading into the 2020 presidential campaign.
His decision sets up a showdown in the Democratic primary with Rep. Darren Soto, the first Florida congressman of Puerto Rican descent, who succeeded Grayson after he made an unsuccessful Senate bid in 2016. DeSantis leads by 22 points, 57-35.
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Top CNN reporters Jim Sciutto, Marshall Cohen and Carl Bernstein - of Watergate reporting fame - had bylines on the story. After suggesting to CNN last Wednesday that 'Cohen was an observer and was a witness to Mr.
The survey found DeSantis winning across the board in demographic breakdowns by age, gender, race and media market, with Putnam leading in only one area: the Tallahassee market where his position as Florida Agriculture Commission gets the most attention and has the most sway. The Arizona seat of retiring Republican Jeff Flake, a Trump critic, is considered one of the two top takeover targets for Democrats, along with Nevada.
Florida's Democratic primary is the most crowded since 1978, the year Bob Graham eventually won the governor's race.
McSally is seen as a stronger general election candidate than either Ward or Arpaio, both hard-line conservatives.
Alan Grayson, a liberal firebrand who ignited controversy during his previous tenure in Congress, has chose to run again for his old seat representing a district in Florida.