TAMPA, Fla. -- Florida was, at one time, the state that could sew up the Republican presidential nomination for Mitt Romney and end the primary.

Not anymore. But Romney's overwhelming win here Tuesday night was a big moment for the former Massachusetts governor that fully restored him to frontrunner status, and dealt a major blow to former House Speaker Newt Gingrich.

Romney won convincingly, with 46.4 percent to Gingrich's 31.9 percent, with 100 percent of the vote counted. Former Sen. Rick Santorum (R-Pa.) and Rep. Ron Paul (R-Texas) trailed behind, with 13.4 and 7.0 percent, respectively.

Romney began his victory speech by addressing head on the growing concerns in the GOP about the nastiness of the primary fight between him and Gingrich, noting that Democrats have watched the brawl and "comfort themselves with the thought that a competitive primary will leave us divided and weak."

"I've got news for them. A competitive primary does not divide us, it prepares us. And we will win," Romney said to a cheering crowd.

But Romney saved much of his most aggressive rhetoric for President Barack Obama , a clear sign that he has watched and learned the way that Republican voters respond to Gingrich's willingness to speak bluntly and forcefully about the incumbent president. Romney's speech was a succession of swipes at Obama.

"In the State of the Union address, the president actually said these words. He says, 'Let's remember how we got here,'" Romney said, referring to the nation's prolonged economic slump. "Don't worry Mr. President. We remember exactly how we got here. You won the election."

"Leadership is about taking responsibility, not making excuses. Mr. President, you were elected to lead. You chose to follow. And now it's time for you to get out of the way," he said.

Romney said Obama's idea of a free economy, "is to send your money to his friends," and he said if elected president, he would help "build an America where hope is a new job with a paycheck, not a faded word on an old bumper sticker."

"I stand ready to lead this party and to lead our nation," Romney said. "My leadership will end the Obama era and begin a new era of American prosperity."

It was by far one of Romney's strongest speeches of the campaign, and the crowd's wildly enthusiastic response validated that.

The news Tuesday night that Romney will begin receiving Secret Service protection on Thursday added to the sense that he had taken a very real step toward becoming the nominee.

Gingrich was unbowed.

"We are going to contest every place and we are going to win and we will be in Tampa as the nominee in August," he said .

Romney's win in Florida put him in solid position to ultimately claim the GOP nomination. At points throughout the past year, many political observers thought that the race would be over if Romney won here.

But the race will go forward at full speed, largely because Gingrich has dug in his heels and angrily denounced those who say his candidacy is over after a Florida loss. That chorus was joined Tuesday by Florida Gov. Rick Scott (R) and Sen. Marco Rubio (R-Fla.).

Defiantly, Gingrich said this week he'll fight tooth and nail, "state by state," all the way to August and the Republican convention, which, by the way, will be right back here in this city.

There are a few reasons why Gingrich could actually deliver on his threat.

Gingrich has been left for dead twice already in this primary, first when his campaign imploded last June and then again in early January, when his lead in the polls plummeted into the abyss. He has the guts, the brains, the anger, and -- for now -- the money to carry him along for some time. And there is still resistance to Romney from a significant portion of the Republican Party , particularly at its grassroots.

A total of 39 percent of GOP voters told CBS News in exit polls that they were not satisfied with their choices of candidates.

Lastly, more states are awarding delegates proportionally in Republican primaries than ever before, and the political universe -- thanks to the epic 2008 Democratic primary contest between Obama and Hilary Clinton -- is more aware than any time in recent history of why delegate counts are important. A candidate needs 1,144 delegates to secure the nomination. With his victory in Florida, Romney won 50 delegates and is up to 87 in all , ahead of Gingrich's 26, Santorum's 14, and Paul's 4.

The big question mark for Gingrich is how long he can run his campaign if he loses steam and donors, and if the biggest donor of all -- Las Vegas casino magnate Sheldon Adelson -- decides to stop depositing $5 million checks in the bank account of the super PAC supporting Gingrich.

It was a big win for Romney, and it halted the wave of momentum behind Gingrich as he entered Florida just over a week ago, after winning South Carolina. But it was also absolutely mandatory for Romney to keep doubts about his candidacy at bay. And it didn't drive a stake through Gingrich's heart.

There is an air of uncertainty now about what lies ahead. Gingrich faces a full month before there are any more contests that favor him. It's not yet clear how the various campaigns will handle the odd pause in action between a quick burst of smaller state contests in early February and the Arizona and Michigan primaries on Feb. 28.

It's a nearly three-week gap where no votes will be cast. The Gingrich camp, sources said, will campaign in states where they are weak during the February lull, leaving Super Tuesday states that are advantageous to Gingrich -- Georgia, Tennessee and Oklahoma -- well enough alone. There are eight other states that will vote or caucus on March 6: Alaska, Idaho, Massachusetts, North Dakota, Ohio, Vermont, Virginia and Wyoming.

Gingrich will seek to build strength in those places. In Virginia, he can't because he's not on the ballot and is ineligible for the state's 49 delegates, a result of the way he has run a small and unorganized campaign. In places like Massachusetts, he probably won't spend any time, since that is the area where Romney is from.

The Romney campaign will likely have plenty of ammunition to use against Gingrich, simply because Romney will have won Florida and is expected to perform very well in Nevada on Saturday and in the early February caucus states.

A senior Romney adviser told The Huffington Post they expect the dead period to "freeze in place" the state of the race, and that Romney will focus on fundraising to boost up the campaign coffers, as well as deliver a policy speech or two. This state of affairs could end up putting even more pressure on Gingrich to try to produce some kind of breakout moment, to jump start his campaign (again).

"Newt's going to have to figure out how to go after Mitt without turning people off," said Al Cardenas, the chairman of the American Conservative Union, who attended Romney's rally but has not endorsed him. "That's not an easy assignment, given the fact that there won't be a lot of opportunities and the opportunities that may exist, he's not going to do that well. So he's gotta figure out, 'How do I survive February in order to be competitive in March?'"

Romney's win on Tuesday capped a week of "gutter politics," as Santorum put it , with Romney and Gingrich trading blows that seemed only to grow more vicious and personal by the day. It marked a new chapter for Romney, who showed a willingness to throw verbal punches on the trail that he had up until now allowed his campaign to deliver for him.

And the Romney campaign's concerted attacks on Gingrich following his huge win in South Carolina on Jan. 22 drove Gingrich to distraction and to angry, scattershot counter attacks that risked making him look desperate. Romney described him on Monday as "flailing."

Gingrich's anger was evident after his loss. While Santorum and Paul called Romney to congratulate him on his win, Gingrich did not, a Romney source told CNN's Candy Crowley .

Former Sen. Jim Talent (R-Mo.), one of Romney's top backers and an informal part of his campaign, defended the Romney campaign's broadsides at Gingrich.

"Everything we've raised are aspects of the speaker's professional and public record. This is what campaigns are about. You contrast on the record," Talent told HuffPost. "We've avoided the personal stuff. We really have. I don't know what Newt thinks or [is] saying but I think we've been very fair."

The two candidates will be under pressure from those in their party who have been distressed by the nasty tone of the race to get back to discussing substance and policy, and to restore some measure of civility as the race moves forward. Santorum himself worked this theme into a speech on Monday, and could begin scoring political points if Gingrich and Romney continue their food fight.

Santorum and Paul skipped Florida on Tuesday and held election night parties in Nevada, where the candidates will compete for that state's 28 delegates when Republicans caucus on Saturday.

Elise Foley contributed reporting from Tampa and Amanda Terkel contributed reporting from Orlando.