MIAMI, Fla. (CBSNewYork/AP) —  Mitt Romney walked away with a commanding victory in the Florida primary Tuesday night, rebounding from defeat a week earlier and taking a major step toward the Republican presidential nomination. Despite the one-sided result, Newt Gingrich vowed to press on.

“I stand ready to lead this party and to lead our nation,” Romney told the jubilant crowd gathered at the Tampa Convention Center, all but calling on the fractured GOP to rally behind his candidacy.

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The former Massachusetts governor, who lost to Gingrich in South Carolina just 10 days ago, also tried to cast what’s expected to be a long and bitter nomination fight as a positive for the Republican Party.

“A competitive primary does not divide us. It prepares us,” Romney said after a relentlessly negative fight for all of Florida’s delegates to the GOP nominating convention this summer.

He suggested that negative attacks by the remaining candidates in the race — Gingrich, former Pennsylvania Sen. Rick Santorum and Texas Rep. Ron Paul — would be a test for his candidacy that would prepare him for the general election rather than a gift to Democratic President Barack Obama.

Romney also offered what might be his most definitive argument yet for his presidential candidacy: Only he could lead the GOP and the country. His brief speech was filled with direct contrasts from Obama, specifically on the topic of leadership.

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“My leadership helped build businesses from scratch. My leadership helped save the Olympics from scandal and give our American athletes the chance to make us all proud, and they did,” Romney said. “My leadership will end the Obama era and begin a new era of American prosperity.”

The winner-take-all primary was worth 50 Republican National Convention delegates, by far the most of any primary state so far.

But the bigger prize was precious political momentum in the race to pick an opponent for President Obama this fall.

With many Floridians transplanted northeasterners and former metropolitan area residents, Romney used New Jersey Gov. Chris Christie to defend him against Gingrich’s attacks on his character.

“Mitt Romney is man of impeccable character,” said Christie. “It offends me that Newt Gingrich would attack the character of Mitt Romney.”

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(TM and Copyright 2012 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)