But the cost of the victory may only become clear as the year winds on.The Texas governor should make “an apology to the people of South Carolina for running such a low campaign”, said Mr McCain on Friday night. Mr Bush accuses him of being just as vicious, saying that he has managed to “take the high horse and then claim the low road”.The race for the Republican nomination quickly took a negative turn, as Mr Bush attacked Mr McCain’s reputation and integrity after the latter’s shock victory in the New Hampshire primary. Mr Bush had begun the year by presenting himself as a reconciler of differences within the party, but he used those differences as wedges in South Carolina, storing up some big problems for the future.At Bush events, one Republican has been saying that Mr McCain, a former US Navy pilot and Vietnam prisoner of war, had betrayed veterans. Mr Bush’s campaign and groups working with it used telephone banks, blast faxes and television ads to attack his rival’s character. He was accused of fathering illegitimate children, doing favours for campaign donors and supporting abortion, and called a Communist spy.The aim was twofold. Firstly, Mr Bush’s campaign wanted to raise Mr McCain’s “negatives” – the aspects of the candidate that voters disliked.

By the end of the campaign, 15 per cent of voters saw the Senator in a negative light – but the figure was the same for Mr Bush. If that goes much higher, neither can win the presidential election.Secondly, the Bush camp wanted to consolidate his Republican base. The Texas governor has firmly secured the conservative wing of the party, but in the process lost its moderate elements to Mr McCain. The South Carolina race has exposed, rather than healed, the gaps in the party.

This is a bad omen: Robert Dole lost the 1996 presidential election in part because he was weakened after a very nasty primary race.But Mr Bush has made it clear that “No More Mr Nice Guy” has become his slogan. His campaign strategist, Karl Rove, is a master of negative campaigning and the South Carolina race bears his stamp. When Mr Bush faced Anne Richards in the 1994 Texas governor campaign, he focused attacks on her integrity. She snapped under the pressure saying: “You just work like a dog, you do well … and all of a sudden you’ve got some jerk running for public office telling everybody it’s all a sham.”"It showed that she was consumed with him … her focus was on trying to prod him and so we knew that we had her,” Rove said afterwards.The same strategy has been pursued against Mr McCain.