Mitt Romney is headed for a decisive victory in Tuesday’s Florida primary, if two new statewide polls out Sunday are the least bit accurate.

Romney leads Newt Gingrich by margins of 11 percent and 15 percent in the surveys.  If he were to prevail by that advantage on Tuesday, it would represent an abrupt reversal of last weekend’s South Carolina vote, which Gingrich took by a double-digit score.

An NBC News/Marist poll, released this morning, had Romney leading Gingrich 42 percent to 27 percent.  Former Pennsylvania Senator Rick Santorum was third, with 16 percent, andRep. Ron Paul of Texas, who is not aggressively contesting the Florida primary was last with 11 percent.

A Mason-Dixon Poll for the Tampa Bay Times and Miami Herald offered similar findings.  It showed Romney with 42 percent among likely GOP primary voters.  Gingrich had 31 percent.  Santorum was third with 14 percent and Paul was last at 6 percent.

Florida, the largest and most diverse state to vote so far this year, is the fourth most populous in the country.  A big Romney victory on Tuesday could make it all but impossible for any of his rivals to stop him from gaining the nomination. 

The internal results of the NBC/ Marist survey were a mirror image of the exit poll findings in South Carolina, a more socially conservative state with a larger proportion of fundamentalist Christian voters that—up to now, at least—has always voted for the eventual nominee.

Romney has opened up a huge gender-gap advantage over the thrice-married Gingrich, whose second wife recently made controversial remarks about her ex-husband.  Women voters are essentially deciding the Florida race, according to the Mason-Dixon poll. It showed women favoring Romney over Gingrich by 19 points.  Men divided evenly between Romney and Gingrich in the Mason-Dixon poll.

Likely Republican voters in Florida saw Romney as the GOP contender best able to defeat President Obama in the fall, a key consideration throughout the country for Republicans.  

For much of this month, Gingrich has been battered over the airwaves in Florida by a negative ad attack from the Romney forces that reached hurricane force over the past week.  The impact was reflected in the widening gap between Romney and Gingrich, and in another finding of the NBC poll: It showed that Florida voters now regard  Santorum, who has been spared ad attacks from his rivals, as better able to defeat Obama than Gingrich.

paul.west@latimes.com