ALL OVER BUT THE GROUSING:

Roughly half the GOP primary vote in South Carolina are mainstream Republicans, simpatico with Romney's pragmatic pitch that he's the only player in this field who can beat President Obama.

Moreover, Romney is the beneficiary of a fragmented anybody-but-Mitt vote that makes it easier for him to win with less than an absolute majority.

For openers, Rep. Ron Paul's libertarian loyalists guarantee him a minimum of 15 points wherever he runs, denying those votes to the other not-Mitts.

For the same reason, Romney's strategists were delighted that Texas Gov. Rick Perry decided not to bow out after all and to compete in South Carolina.

"We'd be happy to loan him our plane (to campaign)," a Romney operative cracked.

And Gingrich and Rick Santorum will be fighting over many of the very same voters.

Even without the tailwind from Tuesday's win, Romney was ahead in Florida (voting Jan. 31) and has money to burn.

He is already advertising there and aggressively wooing name-brand Republicans.

Several GOP sources say they won't be surprised if popular former Florida Gov. Jeb Bush, whose father has already endorsed Romney, follows suit soon.

In a worst-case scenario, Romney is the only candidate with the organization and cash to wage a 50-state war of attrition if necessary.

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