Mitt Romney’s resounding win in the Florida GOP primary is a warning shot to any Democrats who think he will be a soft target.

Romney and his advisers showed dexterity, smarts and toughness in retooling his campaign within hours of his stinging loss in South Carolina on Jan. 21. Romney followed the revised roadmap to a tee.

He shredded Newt Gingrich in Florida’s two debates, leaving him flailing in the campaign’s closing days. He summoned a host of prominent Republicans to denounce Gingrich. And he regained his image as the person best positioned to take on President Obama this fall.

There is still time for things to go wrong for the former Massachusetts governor. Gingrich might resuscitate his campaign, as he did after his Iowa collapse, although GOP insiders say the odds are not good.

If Romney does become the nominee, his highly negative campaign tactics may hurt him among independent voters. And Obama might do a much better job of hitting Romney’s record at Bain Capital and his switches on key policies over the years.

But the smug comments by some Democrats who said Romney is soft, untested and unable to take a punch have been obliterated.

“Mitt Romney’s campaign has passed a crucial test and become the kind of campaign we’re going to need to defeat Barack Obama in the fall,” said longtime GOP strategist Terry Holt.

The most impressive thing about Romney’s Florida win is how quickly his team shifted gears after his 12-percentage-point loss to Gingrich in South Carolina. Romney’s team hatched a new strategy hours before the loss was official: Romney would get meaner to make Gingrich madder.

Romney immediately agreed to focus his main attacks on Gingrich, not Obama. He’d highlight touchy subjects such as Gingrich’s consulting work for Freddie Mac, the government-sponsored lender that some Floridians blame for their state’s housing crisis.

The new, tougher Romney made a dramatic debut Jan. 23, at a debate in Tampa. He ripped into Gingrich from the opening bell, saying the former speaker “had to resign in disgrace” in 1998, only to become “an influence-peddler in Washington.”

Gingrich, who had re-energized his campaign with two fiery debates in South Carolina, seemed unsure how to respond.

Romney was even more sure-footed Thursday in Jacksonville. He seemed more focused and more aggressive than Gingrich at nearly every turn.

Romney’s research staff had handed him a crucial bit of information shortly before the forum. Earlier that day, Gingrich had rebuked Romney for owning Freddie Mac shares. Romney’s staff quickly found similar holdings in Gingrich’s financial disclosures. When Romney confronted his rival with the fact on the debate stage, Gingrich was left speechless.

Romney’s team of advisers, including Stuart Stevens and new debate coach Brett O’Donnell, showed the type of flexibility, solid research and fast, incisive thinking that helped Obama beat Hillary Clinton’s highly regarded campaign in 2008.

No campaign strategy is better than its candidate, of course. For 10 days in Florida, at least, Romney displayed a level of discipline and confidence that could worry Obama fans.

To be sure, Romney had advantages in Florida that he’s unlikely to enjoy in the fall, if he’s nominated. Gingrich inexplicably dropped the feisty debate style that helped him win South Carolina. And Romney’s team overwhelmed Gingrich in spending, flooding Florida’s airwaves with attack ads.

Romney’s win “was fueled by a 4.5-to-1 spending edge that he’ll never have as the nominee,” said Obama campaign adviser Robert Gibbs.

Gibbs also said Romney has damaged his image among independent and Hispanic voters by using a “negative tone” and taking hard-right positions on issues such as immigration.

An NBC News-Wall Street Journal poll gives some credence to that view. It found that Romney’s negative ratings with independents have risen 13 percentage points since December.

Some Democrats say those independent voters, crucial in all general elections, will be more receptive to criticisms of Romney’s record at Bain Capital. The corporate reorganization firm has a history of both creating and eliminating jobs.

Gingrich’s criticisms of Bain fell so flat with GOP voters that he abandoned them in South Carolina. Romney has fielded other barbs from his rivals as well, including taunts about his changed stances on abortion, gun control and gay rights, and his push for mandatory health insurance in Massachusetts.

Detractors say Romney’s answers are often evasive or illogical. Maybe so, but that didn’t hurt him much in Florida. He now goes to Nevada, Michigan and other states as a candidate who has proven he can get up after being knocked down.

Some Democrats are impressed.

“Romney’s flaws have mostly surfaced and been addressed, and he got stronger,” said Matt Bennett, a former aide to Al Gore and a vice president of the pro-Democratic group Third Way.