Former Republican Governor Charlie Crist addresses supporters in a waterfront park where he announced his Democratic candidacy for governor during a rally in St. Petersburg, Florida, Nov. 4, 2013. (Steve Nesius/Reuters)

As Florida’s charismatic Republican governor, Charlie Crist was a national star in his party. He declared Ronald Reagan his role model. He came close to becoming John McCain’s vice presidential running mate in 2008.

But on Monday, less than three years removed from his tenure as Florida’s governor and a year after becoming a Democrat, Crist presented himself to voters once again — in a new light.

In a twist of political fate, a man once ridiculed by Democrats as lacking substance and conviction has emerged as their party’s presumptive standard-bearer in the 2014 gubernatorial contest.

If Crist becomes the nominee, the race would take on an unusual character, pitting Florida’s two most recent Republican governors against each other in what surely would be a bitter, expensive and nationally watched competition. At stake is which party controls the levers of power in the country’s most populous swing state ahead of the 2016 presidential race.

Some of Florida’s most prominent Democrats stood with Crist for his formal campaign announcement Monday morning in his home town of St. Petersburg, embracing him as their best hope for ousting Republican Gov. Rick Scott next year.

Scott backers quickly began an ad campaign citing past Democratic criticism of Crist as an opportunistic shape-shifter.

Yet Crist intends to make a case to voters disgusted by partisan warfare in Washington and Tallahassee that his flexibility is a plus.

“The far-right wing seems to want to make much of my party affiliation,” he told cheering supporters and family members, including his Republican parents. “That is precisely what’s wrong with politics today.”

To those who have watched him closely since his humiliating loss in the 2010 U.S. Senate race to Marco Rubio, Crist’s reemergence as a Democrat is hardly surprising. When polls that year showed him likely to lose the Republican nomination to Rubio, largely because of conservative anger about Crist’s support for President Obama’s economic stimulus program, Crist renounced his party affiliation and ran as an independent. He became a Democrat last year and campaigned for Obama’s reelection, speaking at the party’s national convention in Charlotte and using that opportunity to court key players in the president’s fundraising and activist networks.

The Obama machinery was evident immediately on Monday. The president’s 2008 Florida director, Steven Schale, is serving as an adviser, while the campaign has hired Obama media guru Jim Margolis. Several prominent state Democrats appeared with Crist onstage, including longtime former state attorney general Bob Butterworth and former state House Democratic leader Dan Gelber.

The scene underscored how much Florida Democrats want to find a viable gubernatorial candidate. The party has virtually no power in Tallahassee, with Republicans dominating the legislature and occupying every state cabinet seat. Democrats have not won a race for governor since 1994. Polling over the summer showed Crist with a double-digit lead over Scott.

“It’s very expensive to run in Florida,” Gelber said. “Very few people in Florida have any identity other than major sports figures and a precious few elected officials. He is one of the handful that does. And it’s a very positive one.”

Not every Democrat is pleased with the rush to nominate Crist.

The man Crist defeated in 2006, former congressman Jim Davis of Tampa, said he is strongly encouraging Sen. Bill Nelson, Florida’s only statewide elected Democrat, to enter the race. Davis wasn’t ready to say the party had settled on Crist.

“Yesterday’s establishment is not today’s opinion leaders,” he said.

Crist faces a primary challenge from Nan Rich, a liberal former state senator who says her profile is a far better fit for the state’s Democratic voters.

Rich, in an interview, attributed the high-level party support for Crist to his relationship with Obama. “There’s kind of a circle there that has been supportive of [Crist], or supportive of this idea, because they inaccurately and mistakenly believe that Charlie is the only one who can beat Rick Scott,” she said.

Crist and his backers point to key moments that help him stake his claim as a legitimate Democrat.

Among them: his move in 2008 to keep crowded voting locations, many of them heavily African American with large turnout in favor of Obama, open late to allow everyone to cast their ballots; his support for restoring felons’ voting rights; his embrace of Obama’s stimulus plan, which Crist referenced indirectly as his support for helping thousands of teachers avoid layoffs; and his veto of a GOP-backed teacher tenure bill. As a state lawmaker, Crist fought rate increases by power companies, winning praise from consumer advocates.

The long-beleaguered Florida Democrats have been unable to attract another top-tier challenger to Scott.

So as Crist methodically introduced himself to activists, party officials offered their help as advisers and tour guides.

State GOP Chairman Lenny Curry said Republicans will criticize Crist for deciding, after one term, to run for Senate instead of reelection at a time when the state was experiencing an economic meltdown.

“He’s just not a serious person,” Curry said.