After months of buildup and speculation, Republican Gov. Ron DeSantis of Florida is officially entering the 2024 White House race.

Sources familiar confirmed to Fox News that the popular conservative governor will declare that he's a candidate for president on Wednesday at 6 p.m. ET during a conversation with Elon Musk on Twitter.

Along with his announcement, DeSantis is expected to file paperwork with the Federal Election Commission, which officially launches his GOP presidential campaign. His first national TV interview following the announcement will be with Fox News' Trey Gowdy Wednesday at 8 p.m. ET on "Fox News Tonight."

Even though he's been on the 2024 sidelines, DeSantis for months has been in the top tier of Republican nomination contenders, behind former President Donald Trump and ahead of the rest of the field of actual and likely candidates in nearly every GOP primary poll.

Trump and his allies were quick to take aim at DeSantis.

"Announcing on Twitter is perfect for Ron DeSantis," a Trump adviser told Fox News. "This way he doesn’t have to interact with people and the media can’t ask him any questions."

The announcement by DeSantis coincides with his meeting this week in Miami with top financial backers.

RON DESANTIS MOVES CLOSER TO LAUNCHING 2024 PRESIDENTIAL BID

Ron DeSantis in Iowa

Florida Gov. Ron DeSantis speaks to voters on March 10, 2023, in Des Moines, Iowa. (Scott Olson/Getty Images)

A formal campaign kickoff event will likely take place sometime after this week's gathering of top donors and bundlers, but no details have been shared by the campaign.

The blockbuster move by the two-term Florida governor now turns the battle for the Republican nomination into an apparent two-person fistfight between DeSantis and Trump.

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DeSantis, who at age 44 is more than three decades younger than Trump, won his first election as governor in 2018 thanks to a major assist from the then-president. But he became a force of his own as he’s built a political brand that stretches from coast to coast.

The governor saw his popularity soar among conservatives across the country the past three years, courtesy of his forceful pushback against coronavirus pandemic restrictions and his aggressive actions as a culture warrior going after media, corporations and school unions.

Republican Florida Gov. Ron DeSantis

Gov. Ron DeSantis waves after taking the oath of office during his second inauguration in Tallahassee, Florida, on Jan. 3, 2023. (Reuters/Octavio Jones)

DeSantis routinely dismissed talk of a 2024 White House race last year as he focused on his gubernatorial reelection. But he began dropping hints of a possible presidential bid, starting with his reelection victory speech in November after he cruised to an historic 19-point win in Florida, a onetime battleground state. And he reiterated in speeches his pledge that "we’ve got a lot more to do, and I have only begun to fight."

DeSantis, who served in the Navy Judge Advocate General’s (JAG) Corps before being elected to Congress, has showcased that his wins as governor have "transformed" Florida from a top general election battleground "into the nation’s leading red state" and that his policy victories in Florida can serve as a roadmap for the entire nation.

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The governor racked up a slew of conservative policy victories – including a controversial six-week abortion law, tougher immigration laws, restrictions on gender and diversity instruction in schools, and green-lighting the ability to carry a concealed weapon without a permit – during Florida's just-concluded legislative session, courtesy of a GOP super majority in Tallahassee.

DeSantis has traveled across the country in recent months, highlighting his "Florida blueprint" and promoting his newly released book, "The Courage to Be Free."

Writing a book is a rite of passage for many potential and actual presidential candidates. And his travels have taken him multiple times to Iowa, New Hampshire and South Carolina, the first three states to vote in the GOP presidential nominating calendar.

Ron DeSantis in New Hampshire

Florida Republican Gov. Ron DeSantis speaks with customers at Red Arrow Diner in Manchester, New Hampshire, on May 19, 2023. The iconic diner has long been a must-stop for White House hopefuls. (Paul Steinhauser/Fox News)

DeSantis has made a series of moves in recent weeks that indicated a campaign launch would be imminent.

Among them was a move by DeSantis’ political team from the Republican Party of Florida headquarters – where it has been housed following last November’s gubernatorial election – to new offices.

Additionally, a further signal was the move by the governor to sever ties with Friends of Ron DeSantis, his longtime political state committee, in order to comply with federal campaign finance regulations.

DeSantis enters the 2024 race in a relatively strong position. He's firmly in second place, far ahead of the rest of the field of actual and potential Republican White House contenders, but his poll numbers have slipped since earlier this year in relation to Trump.

But when it comes to fundraising, he’s sitting on a massive war chest he built during last year’s gubernatorial reelection campaign. DeSantis set a gubernatorial fundraising record in the 2022 cycle and had $110 million cash on hand in his fundraising committees at the start of the spring. Much of that money could likely be transferred to Never Back Down, a super PAC backing DeSantis' White House bid.

"Gov. DeSantis has earned his place atop the Republican presidential primary field," longtime Republican strategist Colin Reed noted. "DeSantis has a great story to tell, a great record to run on and a young, telegenic family."

Florida Gov. Ron DeSantis inauguration

Florida Gov. Ron DeSantis waves as he arrives with his wife, Casey, and their children, Mason, Madison and Mamie, before his inauguration ceremony outside the Old Capitol, Jan. 3, 2023, in Tallahassee. (AP Photo/Lynne Sladky)

Reed, a veteran of presidential and Senate campaigns, emphasized that "in terms of name ID, in terms of ability to raise money, in terms of his ability to get on any TV show he wants, he’s got all that. He didn’t need to get into the race any earlier."

But because of his powerful position, DeSantis has a large target on his back. And Trump, who’s known for pummeling his political rivals, didn’t wait for the governor to declare his candidacy.

Trump started targeting DeSantis last autumn, nicknaming him "Ron DeSanctimonious." And early this year, the former president charged that the governor was a "RINO GLOBALIST" and began referring to him as "DeSanctus."

Pointing to his support for DeSantis in 2018, Trump argued that if the governor joined him in the 2024 Republican nomination race, "I do think it would be a great act of disloyalty because, you know, I got him in. He had no chance. His political life was over."

And after the news broke Tuesday that DeSantis would launch his presidential campaign, the pro-Trump super PAC MAGA Inc. charged that "this is one of the most out-of-touch campaign launches in modern history. The only thing less relatable than a niche campaign launch on Twitter, is DeSantis' after party at the uber elite Four Seasons resort in Miami."

DeSantis has mostly ignored Trump’s verbal attacks, although he’s occasionally responded. When Trump suggested earlier this year – without offering any proof – that DeSantis was "grooming high school girls with alcohol" during his tenure years earlier as a teacher, the governor said, "I don't spend my time trying to smear other Republicans."

Trump standing behind Ron DeSantis on stage

Gov. Ron DeSantis speaks during at rally headlined by President Donald Trump in Sunrise, Florida, on Nov. 26, 2019. (Jayme Gershen/Bloomberg via Getty Images)

Alluding to those attacks from Trump, Reed said for DeSantis "now comes the biggest challenge and that is his ability to take a punch on the national stage."

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"The former president’s already been swinging at him, and he’s been able to stay out of the fray by virtue of not being a candidate," he added. "Now he’s got to get in there and go toe-to-toe with a guy who throws haymakers like no other. And that’s going to be his biggest test."

DeSantis joins a field that besides Trump also includes Nikki Haley, the former ambassador to the United Nations and former two-term South Carolina governor; Sen. Tim Scott of South Carolina, a rising star in the GOP and fierce fundraiser who just declared his candidacy; and former two-term Arkansas Gov. Asa Hutchinson. Also vying for the nomination are multimillionaire entrepreneur, best-selling author and conservative commentator Vivek Ramaswamy, Michigan businessman and 2022 gubernatorial candidate Perry Johnson, and conservative radio talk show host and former California gubernatorial candidate Larry Elder.

The field will likely also include former Vice President Mike Pence, who's expected to launch a campaign in the coming weeks.

Govs. Doug Burgum of North Dakota and Chris Sununu of New Hampshire are seriously mulling presidential bids, with announcements likely in the coming weeks, and former New Jersey Gov. Chris Christie is expected to announce in the coming days whether he'll launch a second GOP presidential campaign. Former Reps. Will Hurd of Texas and Mike Rogers of Michigan may also launch 2024 campaigns.

The Democratic National Committee, responding to the news DeSantis would officially enter the 2024 race, said that 'launching a campaign for the dozens of people on Twitter Spaces is curious, even for the world’s most online candidate."

And DNC spokesperson Ammar Moussa charged that "what’s even more curious is how DeSantis thinks his MAGA agenda of ripping freedoms from Floridians, banning abortion before many women know they’re pregnant, making it easier for criminals to carry guns, or any other of his extreme planks will resonate with Americans when voters have rejected the MAGA agenda over and over."

NBC News was first to report word of Wednesday's DeSantis 2024 announcement.

Fox News' Rich Edson and Mark Meredith contributed to this report