(Reuters) - White House hopeful Mitt Romney's lead over rival Newt Gingrich has edged up to 12 percentage points in Florida, with just two days remaining before the state's Republican primary, according to results of a Reuters/Ipsos online poll released on Sunday.

Romney, a former Massachusetts governor and private equity executive, was supported by 42 percent of likely Florida voters surveyed in the online poll, down from 43 percent in the same poll on Saturday.

But support for Gingrich, a former speaker of the U.S. House of Representatives, slipped to 30 percent in the poll, from 32 percent a day earlier and 33 percent on Friday.

The momentum in Florida ... really seems to be moving in Romney's direction, said Chris Jackson, research director for Ipsos Public Affairs.

The poll confirmed that Romney's fortunes are turning around in Florida a week after a stinging setback when Gingrich scored an upset win in South Carolina's primary.

Romney has moved ahead of Gingrich in several Florida polls, after turning in his strongest debate performance yet in the seesawing race for the Republican nomination to oppose Democratic President Barack Obama's bid for re-election in November.

The Reuters/Ipsos survey showed Romney also gained when voters were asked who they would support in a head-to-head contest with Gingrich. Saturday's results showed that 53 percent would support him, versus 45 percent for Gingrich.

In the results released on Friday, Romney had led by just 2 percentage points when voters were asked the same question.

Rick Santorum Siphoning Some Gingrich Support?

Former U.S. Sen. Rick Santorum of Pennsylvania trailed well behind with 16 percent support, but he gained ground from 13 percent in Friday's results.

It seems like some people who are leaving Gingrich are moving to the other conservative in the race, Rick Santorum, Jackson said.

U.S. Rep. Ron Paul of Texas was at 6 percent on Saturday, compared with 5 percent on Friday. The small-government libertarian has not been campaigning in Florida.Romney has subjected Gingrich to a blistering run of attack advertisements in Florida. He has assailed Gingrich for leaving Congress under an ethics cloud in 1999 and for being a Washington insider and lobbyist in the years since.

Gingrich denies he ever worked as a lobbyist, but has yet to find an effective way to parry Romney's attacks.

(Reporting By Patricia Zengerle; Editing by Sandra Maler)