Florida's primary today is shaping up to be a showdown between Republicans John McCain and Mitt Romney, with former New York mayor Rudy Giuliani well behind.

Giuliani had skipped the earlier primaries to stake everything on the Florida primary, which has 57 delegates up for grabs and is the last primary before more than 20 states hold their primaries next Tuesday.

"Giuliani's strategy of skipping the early primaries, getting written out of the conversation and staking it all on Florida was either madness or genius. Right now it looks like madness," American University presidential historian Allan Lichtman told CTV's Canada AM on Tuesday.

Giuliani's main claim to fame is being New York's mayor during the terror attack of Sept. 11, 2001.

"He needs to quit talking about 9/11 and dial 911," New York Times columnist Maureen Dowd wrote on Sunday about Giuliani's faltering campaign.

Giuliani, who predicts the winner there will take the Republican nomination, tried to remain upbeat on Tuesday.

"I expect to win it," he said. "You don't contemplate losing it. That isn't something you do on the day of a primary."

Mike Huckabee, the former Arkansas governor who scored an early win in Iowa but nothing since, has barely campaigned in the state.

Polls have McCain, an Arizona senator, and Romney, a former governor of Massachusetts, essentially tied.

However, Giuliani adviser David Frum told Canada AM on Monday that about 30 per cent of Florida's ballots were cast in advance, so that may be a "secret weapon" for Giuliani.

McCain and Romney have been in a bitter battle, with negative ads and reports of dirty tricks on both sides.

Romney has aggressively courted absentee voters and has a significant get-out-the-vote effort. Florida has been hit hard by the economic downturn in the U.S., and so Romney's messaging on the economy is seen to play well.

McCain, 71, has had endorsements from Sen. Mel Martinez and Gov. Charlie Crist, Florida's top two elected Republicans. A number of Florida newspapers have endorsed McCain.

Name recognition and perceived strength on national security issues are also seen as McCain's strengths. The former prisoner of war in Vietnam is expected to do well in parts of Florida with a strong military presence.

However, he has benefited from open primaries where independents can vote. Florida is "closed," meaning it's restricted to registered Republicans. McCain has some detractors among Republicans, who see him as too much of a maverick.

The stakes are high because Florida is a winner-take-all primary and offers the largest number of delegates yet in the primary process. There is no proportional sharing of delegates.

Today's primary comes after Monday's State of the Union speech by U.S. President George Bush.

Lichtman said the speech didn't do anything to excite or inspire Americans and would have no effect on the Republican contest.

Democrats

Today is also a primary day for Democrats in Florida. However, because the state moved up its primary date without permission, Florida won't be allowed to send any delegates to the U.S. Democratic National Convention in August where the nominee will be selected.

The candidates had agreed to not campaign in either Florida or Michigan, another state punished for "leapfrogging." However, New York Sen. Hillary Clinton pressed her opponents to allow delegates from those states to vote at the convention.

"Those decisions will be made after the nomination, not before," Illinois Sen. Barack Obama told reporters Tuesday. "Obviously, I care a lot about the people in Michigan and a lot about the people in Florida. And I want their votes in the general election. We'll be actively campaigning for them."

The Democrats have no primaries before next Tuesday, but there is buzzing in their circles over Monday's announcement by some members of the Kennedy clan, including Sen. Ted Kennedy of Massachusetts, that they endorse Obama.
 
Lichtman said most endorsements "aren't worth the paper they're written on or the breath used to issue them. But this endorsement matters."

The endorsement is "an enormous snub to the Clintons," he said. "The Clintons are burning up about it." It helps Obama sustain the momentum he gained with his Saturday win in South Carolina, he said.

It should help Obama with Hispanics and union members, but it remains to be seen if Obama can overtake Clinton in large states like California and New York, Lichtman said.

With files from The Associated Press