Republican frontrunner Mitt Romney is tipped to win Florida.
Florida, a winner-take-all state where the candidate with the majority of votes carries all 50 delegates, would put Romney well ahead of his closest rival, Newt Gingrich, in the race for the Republican nomination.
Success may, however, come at a cost with fellow Republicans criticising Romney's attack ads on Gingrich which they fear may harm the overall chances of the party.
Florida, which carries a significant number of Electoral College votes (27), is a swing state and one of the most coveted battlegrounds in anygeneral election. It was famously won by George W Bush in 2000 by 534 votes acrossthe state - a fraction of a percentage.
Romney, one of the richest men to run for president in the history of American politics, has flooded the airwaves with attack ads against Gingrich. Although they have been effective, they have been criticised by Republican politicians, including the Florida senator Marco Rubio.
Rubio said: "We've got a lot of great things going on in Florida and I don't want these guys to affect our chance come the fall."
But the value of winning now and the cost of losing later seems to be lost on both candidates on the eve of the critical primary vote, as Gingrich and Romney continued to trade blows and accusations over character, consistency and leadership.
Gingrich has been fighting back with his own now customary invective, attacking Romney for "carpet-bombing with negative ads". Gingrich continues to be sensitive to the millions of dollars that an independent so-called "super political action committee" has been spending to support Romney.
Romney has not been not letting up either. Instead of stepping back and re-focusing on President Obama as he did earlier in the campaign, the former venture capitalist is turning up his rhetoric against the rival from within his own party. He hopes to close the Florida campaign strongly on Tuesday and to push Gingrich as far back as possible.
An NBC News/Marist poll showed Romney with support from 42 percent of likely Florida primary voters, compared to 27 percent for Gingrich.