ST. PETERSBURG — Charlie Crist is running for Florida governor as a Democrat.

The worst-kept secret in politics was confirmed Friday afternoon when the Republican Party of Florida spotted Crist's official filing with the state Division of Elections.

The former Republican governor turned Democrat plans a formal announcement at 10 a.m. Monday at St. Petersburg's Albert Whitted Park, 480 Bayshore Drive SE, but the state GOP beat him to the punch.

"Gov. Crist looks forward to discussing his priorities for moving Florida forward on Monday morning," said Steve Schale, a spokesman for Crist who led President Barack Obama's successful 2008 Florida campaign.

Republicans managed to diminish whatever drama Crist hoped to preside over in his hometown Monday, but it was hardly a secret that Crist was preparing to run against Republican Gov. Rick Scott.

Crist has been courting top Democratic fundraisers from across the state and country in recent months, has launched a new website, and lately is often accompanied by top Democratic strategist Schale. The sleuths at the Florida Republican Party this week also found a "CHARLIE CRIST FOR GOVERNOR — 2014" logo online.

Republican Gov. Rick Scott leaves today for a trade mission to Japan, so he won't be in the state for Crist's official announcement. That won't stop him from responding to it, though.

Let's Get to Work, Scott's political committee, late this week spent more than $500,000 to air a TV ad across the state starting Monday and continuing for two weeks. Seemingly aimed as much at sowing doubts among Democratic primary voters as general election voters, the ad features quotes from Democrats criticizing Crist in the past:

Democrat Alex Sink says, "He failed to lay out a business plan to get Florida out of its worst recession."

Democratic chair Karen Thurman said, "He has done nothing to create jobs . . . his only core belief is personal ambition."

"He's an opportunist," says Tampa's Mayor Buckhorn.

Congressman Kendrick Meek says he "can't be trusted."

Al Gore said, "It's a little unusual to have someone flip-flop and . . . then flop-flip."

Who are they all talking about? This man, Charlie Crist.

Given Scott's stubbornly weak approval ratings in Florida public opinion polls, his campaign has little choice but to try to ensure that the Democrat challenging him is perceived as an unpalatable alternative.

Public polls consistently show Crist beating Scott if the election were held today.

Scott, a former health care executive, spent more than $75 million of his own money to narrowly win the governor's race in 2010, and his backers say he will likely spend closer to $100 million on his re-election. Let's Get to Work has raised more than $18 million.

Crist, 57, faces a primary challenge from former state Sen. Nan Rich of Broward County, who argues that she is the true Democrat in the race. But Rich, 71, has raised little money and has yet to show she is a viable candidate.

Crist, a former state senator, education commissioner, attorney general and governor, has been a champion fundraiser, but that was as a Republican. One big advantage for him is Obama, who asked Crist to speak at the Democratic National Convention last year and whose political team has introduced Crist to top money-raisers from New York to California.

No elected official in Florida campaigned harder for Obama in Florida in 2012, and despite his GOP history, Crist has received enthusiastic receptions at recent gatherings of Democratic activists and teachers union members.

"Charlie Crist has now officially filed to run for the position he once abandoned," Florida Republican Party chairman Lenny Curry said Friday. "When Florida needed Charlie Crist the most during difficult economic times, he ran away. If he really wants to be governor now, why did he quit the first time?"

Under state election laws, Crist needed a campaign account in order to pay for a stage and other equipment at Monday's official campaign announcement. That apparently is how the state Republican Party managed to announce Crist's candidacy first.