A newly competitive John McCain tore up his campaign schedule and raced to Iowa yesterday with new polls signalling one of the most remarkable political comebacks of recent times.

Mr McCain, who had largely abandoned Iowa after polls showed him as an also-ran there, returned on the eve of its caucuses having suddenly leapfrogged into third place. His resurgence in the “Hawkeye state” comes as two new polls show him overtaking Rudy Giuliani as the national Republican front-runner.

Mr McCain, who was largely written off last summer after his campaign fell apart, hopes that a strong third-place finish in Iowa will give him unexpected momentum when New Hampshire votes five days later, a state where he has opened up a small lead over Mitt Romney, his chief rival, for the first time.

Mr McCain, seeking at 71 to become the oldest first-term president in US history, had planned to campaign in New Hampshire while his rivals tore across Iowa on the final full day of campaigning before caucus night.

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But with the Des Moines Register poll placing him third, he abandoned the “Granite state” and began a 30-hour bus tour of Iowa, speaking in diners, ice-cream parlours and school gymnasiums. As he arrived, a Pew national poll showed him on 22 per cent, two points ahead of Mr Giuliani, the longtime front-runner. In an extraordinary admission, he also told a voter that if elected, he might just serve one term in the White House, because of his age.

Mr McCain’s political resurrection is the latest twist in the highly volatile Republican race. Mr Romney, who has spent millions of his own fortune to establish himself as the unassailable Republican candidate in Iowa and New Hampshire, is battling Mike Huckabee for first place in Iowa, and Mr McCain for supremacy in New Hampshire. Both are too close to call.

Mr Romney, seeking to become the first Mormon president, has clawed back to parity with Mr Huckabee in Iowa after losing his lead in November. He has unleashed a series of attack adverts against the former Arkansas Governor, who has not helped himself in recent days after several stumbles on foreign policy, his greatest vulnerability.

Mr Huckabee, continuing his sometimes freewheeling campaign, spent Tuesday campaigning with Chuck Norris, the former world karate champion and Hollywood action hero. Last night he left Iowa and flew to California to record an appearance with Jay Leno on his Tonight show.

Before he left, Mr Huckabee, a Baptist minister, appeared before a meeting of sympathetic bloggers, telling them they were “doing the Lord’s work” for promoting his once-long-shot campaign on the internet.

He then headed to a rally for 2,000 people at a nightclub, where he grabbed a bass guitar and, with his rock’n’roll band Capitol Offense, belted out numbers such as Twist and Shout and Blue Suede Shoes.

At a pizza parlour in Sergeant Bluff, he underlined the importance of turning out support, saying: “Don’t go alone. Take people with you. Fill up your car. Rent a van. Hijack your church’s bus, whatever you’ve got to do to get people to the caucus who are going to vote for me.”

Mr Huckabee is relying on the energy of Iowa’s evangelical Christians, who make up 40 per cent of Republican caucus-goers. Mr Romney, meanwhile, is relying on brutal efficiency and the sophisticated ground operation he has spent months, and tens of millions of dollars, building.

In appearances across Iowa, he adopted a more positive tone after the recent attacks on Mr Huckabee and Mr McCain, although the bitter exchanges continued. Mr Huckabee’s campaign manager said in one interview that he wanted to knock Mr Romney’s teeth out. McCain aides continued to mock Mr Romney for suggesting that presidents do not need foreign policy experience.

Thirty miles away, at a rally in Ames, Mr Romney made frequent references to his wife of 38 years and five sons. “We will do our best to show people around the world that there are pretty good folk in the White House and this is how families – moms and dads – are supposed to work,” he said. He suggested that his family would not sully the White House, and that the Clintons did.

Mr Giuliani is trying to defy history by ignoring the early states and focusing on the delegate-rich later contests. On caucus day in Iowa he will campaign in Florida. Fred Thompson, the former senator and Law & Order star, is hoping for a third-place finish in Iowa to boost his candidacy.

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