WASHINGTON (AP) ― Polls show Newt Gingrich will likely be clobbered by Mitt Romney in Tuesday’s pivotal Republican primary election in Florida, even though the former speaker of the House of Representatives crushed Romney last weekend in South Carolina. Money for television attack ads appears to be a key factor in the former Massachusetts governor’s resurgence.

Overall spending figures show Romney and his supporters having outspent Gingrich in the Florida campaign by at least five to one.

That likely is reflected in the latest NBC/Marist poll which shows Romney with backing from 42 percent of likely Florida Republican primary voters and Gingrich slipping to 27 percent.

Figures made available to the Associated Press showed Romney was spending $2.8 million to air television commercials in the final week of the Florida campaign.

In addition, a group supporting him, Restore Our Future, was spending $4 million more, for a combined total of $6.8 million.

By contrast, Gingrich was spending about $700,000, and Winning Our Future, a group backing him, an additional $1.5 million. That was about one-third the amount for the pro-Romney tandem.

A major reason so much money has been flooding into the 2012 U.S. presidential race is a 5-4 ruling by the Supreme Court. In its decision two years ago, the court, which is divided between five conservative justices and four in the liberal camp, ruled that free speech rights guaranteed by the First Amendment to the U.S. Constitution prohibit the government from limiting corporate and labor union spending for political purposes.

The ruling reversed a lower court decision that prevented the nonprofit corporation Citizens United from airing cuts from a film critical of Hillary Rodham Clinton during the 2008 presidential campaign. At issue was whether the group could advertise the film in broadcast ads featuring Clinton’s image.

That was initially held to violate 2002 campaign finance reform legislation.

The ruling overturned a century-old restriction and prompted President Barack Obama to take the highly unusual step of criticizing the justices’ action in his 2010 State of the Union address to Congress, with several members of the high court in the audience.

“Well, I don’t think American elections should be bankrolled by America’s most powerful interests, and worse, by foreign entities,” Obama said in that nationally televised speech.

“They should be decided by the American people, and that’s why I’m urging Democrats and Republicans to pass a bill that helps to right this wrong.”

That prompted an irked Justice Samuel Alito, a conservative appointed to the high court by President George W. Bush, to shake his head and mouth the words, “Not true.”

The Supreme Court’s Citizens United ruling has drawn a negative opinion from a top European anti-corruption organization that is calling for more, not less, transparency for outside groups that give millions to support political candidates.

The Council of Europe’s Group of States against Corruption ― know as Greco and which counts the U.S. as a member ― has warned against the impact of growing “soft money” political financing from groups known as Super Political Action Committees, or Super PACS.

The ruling has opened a cascade of spending on behalf of candidates that formerly was not available, and contributed to the Republicans’ huge gains in the 2010 elections in which they took control of the House of Representatives, picked up Senate seats and won key governorships.

The decision has already helped shape the 2012 Republican presidential nomination battle. Backers of a candidate are allowed to form Super PACs, which are allowed to spend unlimited amounts to support a candidate. The only legal restriction is a requirement that the groups do not coordinate their activities with the campaign organization of the candidate they support.

When Gingrich surged in the polls in December, Restore Our Future, the Super PAC set up by Romney supporters, poured millions of dollars into negative TV ads attacking Gingrich in the runup to the leadoff Iowa caucuses. A badly outspent Gingrich ended up finishing fourth in the Jan. 3 caucuses.

Gingrich’s campaign might have folded up were it not for Winning Our Future, a Super PAC formed by his supporters. A single donor, casino magnate Sheldon Adelson, donated $5 million to the group, which used the money for an anti-Romney documentary attacking his record as CEO of a private equity firm and negative TV ads seen as a key factor in Gingrich’s comeback victory in last weekend’s South Carolina primary that gave his campaign new life.

The OpenSecrets.org Website, run by the independent, nonpartisan and nonprofit Center for Responsive Politics, tracks Super PAC spending and found a big edge for Romney backers in Super PAC spending .

As of Sunday, OpenSecrets said the pro-Romney Super PAC has spent $16.6 million in advertisements ― most of them attacking Gingrich and some targeting former Pennsylvania Sen. Rick Santorum, who edged out Romney in Iowa only to fade in later contests. Restore Our Future draws heavily on donors from the financial industry donors working at such firms as Goldman Sachs and Bain Capital, which Romney co-founded.

By contrast, OpenSecrets said the pro-Gingrich PAC has spent $3.5 million against the Romney candidacy. Its main source of funding has been pledges of $5 million each from Adelson and his wife, Miriam. No other candidate in the presidential race appears to rely so heavily on the fortune of a single donor.

Adelman is an extreme conservative and staunch backer of right-wing Israeli politicians. Gingrich has held policy positions that would match Adelson’s regarding U.S.-Israeli relations, including a pledge to issue a directive on his first day as president to relocate U.S. embassy from Tel Aviv to Jerusalem. That would enrage Palestinians who demand that part of Jerusalem be their capital in any future two-state solution.

The Republican front-runners are not alone. Priorities USA Action, which backs President Barack Obama, has assembled $3.1 million even though the president does not have an opponent yet.