All the signs indicate that the early presidential battleground of Florida is Mitt Romney territory.

The former Massachusetts governor finished a strong second here in the 2008 Republican presidential primary. He would almost certainly have the money to compete on Florida’s costly television airwaves. And in a big state where the nation’s economic ills are magnified — more people are out of work, more homes are under foreclosure — a candidate running as a turnaround specialist could resonate.

Yet by all accounts, the race to win Florida, probably the first big state on the 2012 primary calendar, is wide open.

So it was that Tim Pawlenty touched down here after announcing his candidacy Monday in Iowa. In a 24-hour sweep through the Sunshine State, he raised money, expanded his Rolodex and won over some prominent GOP operatives who backed Romney or others in 2008 but are looking for a fresh face this time.

“This is a place that’s open to people from other places,” Pawlenty, a former Minnesota governor, said in a brief interview Tuesday in the Coral Gables office of Ann Herberger, a top Romney fundraiser in 2008 and a longtime adviser to former Florida governor Jeb Bush who is now guiding Pawlenty through Florida’s vast Republican orbit.

“This is a dynamic, open place, and I think it’s going to be favorable to me,” Pawlenty added. The Florida campaign, he said, “is not only an opportunity. It’s a necessity.”

Earlier, he told a bank of local news cameras: “Florida is one of the big horses we’ve got to ride.”

It’s a horse all the candidates have to ride — at least those who hope to become the Republican nominee. Florida, after all, is where John McCain sealed the nomination three years ago.

The 2012 GOP primary calendar remains fluid, but Florida expects to be fifth, holding a primary sometime in March after voting is finished in Iowa, New Hampshire, South Carolina and Nevada.

“Florida is the first state whose primary will really mirror the nation,” said Sally Bradshaw, a longtime GOP operative here who signed up to work for Mississippi Gov. Haley Barbour but has not backed another candidate since Barbour bowed out.

“There’s so much diversity here, you have to win Florida to be the nominee,” Bradshaw added. “The electorate here is largely undecided. Voters in Florida are not focused. We’re not Iowa, we’re not New Hampshire or even South Carolina. People here have not begun to pay attention.”

Unlike in the other early states, no candidate has particularly strong roots or an imposing network of support here. The Florida Republican Party will host a straw poll in September that could give a shot in the arm to a candidate who mobilizes grass-roots supporters.

This is an opportunity for all the major candidates, but perhaps most for Pawlenty and Jon Huntsman Jr., a former Utah governor and former ambassador to China who has not officially declared a bid. Both underdogs are jockeying to establish themselves as the leading challenger to Romney, who, though also an unofficial candidate at this point, is the presumptive front-runner.

Huntsman would locate his national campaign headquarters in Orlando, an unusual move that signals he would compete vigorously in Florida.

“We believe it’s wide open here, and we believe that Governor Huntsman will have a message that will be attractive to Florida Republican voters,” said Susan Wiles, who managed Rick Scott’s winning campaign for governor in 2010 and is now working for Huntsman.

For Romney, Florida is critical. He is expected to also compete hard in other states, such as New Hampshire, where he owns a home and has been a regular presence since the last campaign. But it is difficult to imagine Romney or anyone else winning the nomination without winning Florida.

At Romney’s Boston headquarters, strategists see the state as significant enough that they have scouted for a firm to help oversee a Florida campaign.

“Florida is without question a must-win state — absolutely,” said Ned Siegel, Romney’s Florida co-chairman and a former ambassador to the Bahamas under President George W. Bush.

Romney was raising money Tuesday at the Jacksonville Jaguars’ football stadium, and he is planning to return to the state June 14-16. His team here thinks his message of fixing the economy is particularly resonant in Florida, where the unemployment rate is 10.4 percent, above the national average.

“We’ve hit bottom, and all we’re doing is bumping on the bottom, and we need someone who understands how to create economic engines,” Siegel said.

Still, Pawlenty’s and Huntsman’s advisers believe that Florida could be theirs for the taking. Perhaps the biggest catch is the endorsement of Jeb Bush, and confidants said he intends to remain neutral. But that didn’t stop Pawlenty’s team from highlighting some Twitter love from Bush after Pawlenty’s Iowa announcement speech: “I admire truth telling and t-paw sure did it to open his campaign,” the former Florida governor tweeted.

Herberger and former Bush adviser Justin Sayfie are helping recruit fellow Bush insiders, as well as other big Florida names, to Pawlenty’s team. Prominent donors Fred Pezeshkan and Bill Schoen are with Pawlenty, as is Martin Garcia, a lawyer who hosted the candidate at his Tampa home Monday night for a fundraiser.

“Florida is up for grabs,” said Phil Handy, who chaired McCain’s campaign here and is co-chairman of Pawlenty’s state effort. “This will be the great testing ground.”

Staff writer Dan Balz in Boston contributed to this report.