TO stand a chance of being the Republican nominee to take on Barack Obama in this year's presidential election, Newt Gingrich had to win the South Carolina primary.

Another victory for Mitt Romney, pictured below, to go with his cruise in New Hampshire and a virtual tie in Iowa, would have ended the contest.

Gingrich knew this, even publicly accepted it, so in the final week of campaigning in this socially conservative, proudly Confederate state, he went on the attack, seeking out confrontation wherever it could be found.

If he does manage to scrape a win, as exit polls at the time of going to print suggest he will, it may have more to do with his broadsides against welfare culture and the liberal media than direct criticism of his rival. But in portraying Romney as a "vulture capitalist" who bankrupted American companies and ruined lives while making his fortune, Gingrich has created an enduring theme for the remaining primaries and the election itself.

In the first South Carolina debate, Gingrich was challenged on his suggestion that "black Americans should demand jobs, not food stamps". His answer – directed at moderator Juan Williams, who is black – skilfully played on the politics of racial resentment: "The fact is, that more people have been put on food stamps by Barack Obama than any president in American history."

At a campaign event the next day, a white woman thanked him "for putting Mr Juan Williams in his place".

At the next debate, Gingrich took on the media, describing the first question put to him – about his second wife's account of his infidelity and hypocrisy – as "close to despicable" and "trash". When the host, John King, followed up, Gingrich interrupted him, saying: "I am tired of the elite media protecting Obama by attacking Republicans." The crowd roared its approval.

This pandering to a sense of conservative victimhood plays well in South Carolina, where Republican voters see themselves as authentic Americans, talked down to by urban liberals and dragged down by the poor and lazy. But as the campaign moves into Florida, Gingrich must adopt a different strategy, which will probably place more emphasis on tearing down Romney's claim to have created jobs.

After the New Hampshire primary, Gingrich allies released a short film called When Mitt Romney Came To Town. It describes what happened to four companies taken over by Romney's firm, Bain Capital, interspersing the testimony of workers who lost their jobs with shots of weeds growing through cracked cement at the buildings and graphics showing how much money Bain shareholders walked away with.

Although the documentary has been criticised as selective in its use of facts and a distortion of Romney's record, it has introduced a talking point most analysts did not expect to see until the election. As conservative icon Rush Limbaugh put it on his radio show: "Newt is using the language of the left in going after Romney on Bain Capital. That makes me uncomfortable."

As a multi-millionaire who earned his money in the private-equity business, Romney is vulnerable to accusations that he would look after the wealthy at the expense of ordinary Americans – an especially resonant charge in the Occupy Wall Street era.

Asked why he has never made his tax return public, he gave a stumbling, uncomfortable answer. He later said he would do so in April, without committing to release more than one year's worth of documents. His father, George, released 12 years of tax returns when he ran for president. He also paid 37% of his income in taxes. As the vast majority of Romney's income is from investments, it is classified as capital gains and taxed at just 15%, meaning that he pays far less, proportionally, than the average American worker.

An ABC News documentary revealed that Romney has parked profits in the Cayman Islands, a tax haven. His speaking fees are taxed as income, but at a campaign event he described this as "not very much" – $374,000 in 2010.

This exposed Romney's propensity for sounding out of touch. Other examples include his assertion that "corporations are people too", his proposed $10,000 bet with Rick Perry in a debate and admitting "I like being able to fire people" – quotes that have been ripped out of context and will continue to define his image, alongside the infamous shot of him and his brash young friends at Bain, holding banknotes in their teeth.

Romney is still the overwhelming favourite to win the nomination. But as the campaign moves into Florida, where loyalties have been especially volatile, Gingrich has shown that no subject is off limits if it bloodies his opponent. In that sense, the real winner of the South Carolina primary may have been - Barack Obama.