Cash key to Florida win

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

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

Mr Romney was spending $2.8m on television commercials in the final week of the Florida campaign. In addition, a group supporting him, Restore Our Future, was spending $4m more.

By contrast, Mr Gingrich was spending about $700,000, and Winning Our Future, a group backing him, an additional $1.5m.

A major reason so much money has been flooding into the 2012 US 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 US Constitution prohibit the government from limiting corporate and labour union spending for political purposes.

The ruling reversed a lower court decision that prevented the non-profit corporation Citizens United from airing cuts from a film critical of Hillary Clinton during the 2008 presidential campaign. At issue was whether the group could advertise the film in broadcast adverts featuring Mrs 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 criticising 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,” Mr Obama said. “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 annoyed 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 organisation 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 US 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 PACSco-ordinate, 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 organisation of the candidate they support.

When Mr 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 adverts attacking Mr Gingrich in the runup to the leadoff Iowa caucuses. A badly outspent Mr Gingrich ended up finishing fourth

Mr 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, gave $5m to the group, which used the money for an anti-Romney documentary attacking his record as chief executive of a private equity firm and negative TV adverts seen as a key factor in Mr Gingrich’s comeback victory in last weekend’s South Carolina primary that gave his campaign new life.