A fifth candidate, Fred Thompson, weighed the future of his bid after a disappointing third-place finish in South Carolina.
With Florida next in the nomination fight, Rudy Giuliani and Mitt Romney wasted no time angling for the upper-hand. They heaped criticism on John McCain, the Arizona senator coming off hard-fought New Hampshire and South Carolina victories, hours before he arrived in Miami.
"John voted against the Bush tax cuts, I think on both occasions, and sided with the Democrats," Giuliani, the former New York mayor, said in a television interview. He has yet to win a contest and has staked his candidacy on a win in Florida on Jan. 29, and was sharpening his criticism of his rivals as the campaign came to him.
At a rally in New Port Richey, Giuliani assailed McCain for never running a government. "When you have that executive experience, you have to make decisions and decisions have consequences. ... Some of my opponents maybe don't have that same fervor and that same understanding," he said.
McCain opposed President Bush's tax cuts in 2001 and 2003 but now says he would support making them permanent because doing otherwise would amount to a tax increase.
Nevertheless, McCain told CNN: "Everybody knows how I was part of the Reagan Revolution where we had tax cuts when, frankly, Mayor Giuliani was supporting a Democrat for governor for the state of New York." Giuliani once broke from his party to endorse Democratic New York Gov. Mario Cuomo.
At a news conference, McCain also chided Giuliani for his 0-6 record, saying: "If someone hasn't run a primary, I can understand why they would attack the front-runner."
Romney, buoyed by wins in Nevada, Michigan and Wyoming, portrayed McCain as a consummate Washington insider and himself, a former one-term Massachusetts governor, as just the outsider able to fix Washington.
"He has been in Washington all of his career. And I don't think you're going to see change in Washington by somebody who's been such a part of it all of these years," Romney said before also assailing McCain's votes against the Bush tax cuts.
A former venture capitalist, Romney also took issue with Giuliani, saying "he's spent his life working in the public sector, in the governmental sector" and, thus, doesn't necessarily understand how the economy works.
And so it began.
Recent polls showed McCain, Giuliani, Romney and Mike Huckabee, the former Arkansas governor who won the Iowa caucuses, bunched together in the fight for the lead in Florida.
Overall, the race for the GOP nomination is remarkably wide open, so much so that the prospect of a protracted contest has appeared more likely as each state has voted. Three candidates have won contests in six states thus far, making for no clear front-runner.
Despite the situation, Thompson was expected to bow out after failing to win the states where he had hoped to perform strongly, Iowa and South Carolina. The former Tennessee senator and "Law & Order" actor returned home after delivering a speech in South Carolina on Saturday that sounded like he was calling it quits. He stopped short of doing so but some supporters suspected it would only be a matter of time before Thompson withdraws.
Before South Carolina, several aides had said he probably would need to finish first or a strong second in that race to go forward. Aides didn't expect a decision from Thompson until sometime after the weekend.
With or without him, the Florida race promises to be a dog fight; the stakes are, perhaps, larger now than ever.
Florida offers its winner a whopping 57 delegates to this summer's GOP nominating convention. A victory would provide the winner not only with a hefty purse in the delegate race but also a huge jolt of energy in the run-up to Feb. 5, when nearly two dozen states from coast to coast hold nominating contests.
Hours after the South Carolina and Nevada contests, several candidates sat for TV interviews as they aimed to maximize free media exposure and save money now that the race has moved to a state with expensive media markets. Giuliani commented on ABC's "This Week" and Romney appeared on "Fox News Sunday" and CNN's "Late Edition."
Most of the candidates also planned to spend part of the week raising money, too.
With such a large and expensive battleground to conquer, the type of retail politicking common in some earlier states will largely give way to made-for-TV hanger rallies and photo opportunities intended to make the most of local media coverage.
For most of the candidates, Sunday brought light schedules and a welcome respite from the full-bore campaigning waged since Christmas.
Huckabee was attending a fundraiser at actor Chuck Norris' ranch in Navasota, Texas.
McCain spoke with reporters in the morning in South Carolina but planned no other public appearances. He picked up endorsements from newspapers in Gainesville and Orlando, and prepared to run his first TV ads in the state.
Romney did television interviews from Jacksonville, but otherwise laid low.
Conversely, Giuliani had a full slate of events, five in the Tampa area as he continued his second bus tour of the state in as many weeks. He didn't compete as aggressively as his opponents in the earliest states to vote.
