For Crist, he is hoping to revive a political career that seemingly crashed when he left the GOP and lost an independent run for U.S. Senate to Republican Marco Rubio in 2010.
Crist has a 10 a.m. event scheduled in a park near his St. Petersburg home to kick off his campaign.
"I'm looking forward to Monday and making it official in every way," Crist said Friday. "I just hope that the message that we deliver will lift Florida's spirits and let her know that there's a brighter future tomorrow. And it's coming."
There was little doubt he was getting into the race. He has been preparing a team of advisers and has set up a website for the potential campaign. His addresses to Democratic groups have increasingly sounded like campaign speeches.
"What a surprise," said former state Sen. Nan Rich, who was alone in the Democratic primary until now. "He's been running for a year, he's finally announced and I think everybody knew he was going to do this."
If he succeeds, it will be an amazing turnaround for the person who many thought could be 2008 GOP presidential nominee John McCain's running mate, if not a Republican presidential candidate in his own right.
Republicans have pounded Crist for months anticipating the announcement, calling him a political opportunist who will say and do anything to remain politically relevant.
"He wanted to be in D.C. a couple of years ago, that's where he wanted to solve all the world's problems, and now he feels he wants to be back as governor without any good reason," said Lenny Curry, chairman of Florida's Republican Party. "Rick Scott has a record of success to run on and Charlie has a lifelong 'It's all about Charlie' to run on."
Curry acknowledged that Crist will be a tough campaigner and a formidable fundraiser. Crist's political skills are among the best in the state. His ability to connect with people has often been compared to that of former President Bill Clinton.
Crist's downfall in the Republican Party can be linked to an appearance with President Barack Obama in 2009. The Democratic president hugged Crist during a rally to support a $787 billion federal stimulus package that most Republicans opposed.
Not that there were immediate repercussions. When Crist decided not to seek a second term and entered the Senate race, he immediately received the backing of the Republican establishment in Tallahassee and Washington.
But Rubio, who received his early support from tea party activists, used the image of the Obama hug to begin chipping away at Crist's dominance in the polls and fundraising. When it became clear that Rubio had the advantage in the Republican primary, Crist decided to run as an independent -- essentially burning any bridges he had with the GOP.
Crist lost and took a job with the Morgan & Morgan personal-injury law firm. He then began re-emerging in politics as a Democrat. His wife, Carole, registered as a Democrat first. He then began donating money to Democratic candidates, including Sen. Bill Nelson. He endorsed Obama over Republican presidential nominee Mitt Romney and campaigned heavily for the president. In December, he made the party conversion complete when he tweeted a photo of himself at the White House with his voter registration card.
And he's now embracing the hug with Obama, using it to help win over Democrats.
While there are Democratic activists who are skeptical, he's largely been given a warm reception.
"There are a lot of people that are excited about his announcement; there's another group that's sort of a wait and see," said Screven Watson, a Democratic consultant. "Some people want to see how strong he is, and then equally and more importantly, how is he going to handle the barrage of attacks that are certain to come."
Gov. Rick Scott has a goal of raising $100 million for the campaign. The Republican Party of Florida has already been attacking Crist for months through news releases, emails, Web videos and websites. It even launched ads against him last summer just before Crist spoke at the Democratic National Convention.
"It's weird to me. That is new. I've never had that kind of assault laid on me when you're not even a candidate yet. It's a little peculiar," Crist said last weekend, adding that the attacks are only going to get worst. "I don't have any fear. I really don't."
And he said he'll have plenty to say about Scott.
"I'll talk about the disappointment and despair that I think this administration has brought on my fellow Floridians and our environment and our education and our ethics. Florida's suffering and she deserves better," Crist said.
Crist has earned the backing of many prominent Democrats. Steve Schale, who ran Obama's 2008 Florida campaign and was a top Florida adviser during his 2012 re-election, is advising Crist. Former House Democratic Leader Dan Gelber has also been helping Crist.
Crist has been well-received at Democratic Party events.
"More than I could ever dream for. I've been overwhelmed by the kindness," Crist said during a state Democratic Party conference last month.
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