Mitt Romney's impressive victory Tuesday makes it very likely that we will look back on the Florida primary as the contest that determined the 2012 Republican nomination.
To be sure, the campaign fight will go on, and Romney is by no means assured of a sweep of the relatively few February contests.
Newt Gingrich has vowed to run all the way to the convention, whatever the odds. He has shown similar determination in the past.
He ran and lost twice for Congress before he was first elected in 1978. He saw his party lose seven straight elections for the House before he led it to its first majority in 40 years in 1994. Gingrich sees himself as a world historical figure, whose destiny should not be forestalled by a few weeks of negative ads and a couple of subpar debate performances. He's also pumped up by anger.
Rick Santorum has shown similar determination, in Pennsylvania and in this cycle. He made hundreds of campaign appearances in Iowa, New Hampshire and South Carolina with no perceptible impact in the polls until he hit double digits in Iowa at Christmastime, two weeks before the caucuses. Santorum sees himself as a principled leader, unafraid to take political risks.
It would be severely out of character for either to withdraw. And neither has any other commitments on his calendar.
As for Ron Paul, he believes, not without cause, that his message of abolishing the Federal Reserve, legalizing marijuana and withdrawing from much of the world has been gaining resonance and attracting followers. He doesn't expect to be president anyway, so why not take advantage of this chance to get the message out even more?
The first February contest is the Nevada caucuses on the fourth. Romney won easily four years ago, thanks in part to the high turnout of his fellow Mormons. But the Nevada caucuses had never been held before, and turnout was a low -- 44,000 in a state of 2,700,000 people.
It's likely to be higher this time, with a lower Mormon percentage, and in a state where Republican primary voters chose Sharron Angle in 2010.
The Maine caucuses start, but don't finish, on Feb. 4. Romney forces are confident there, but Maine Republicans nominated and elected a very conservative governor in 2010.
Three days later, on Feb. 7, come the caucuses in Minnesota and Colorado. Romney won both in 2008, when he was the only Republican candidate with much of a caucus organization.