At least eight viable candidates to be the next president of the United States were preparing yesterday for a frantic final fortnight before the first American voters deliver their verdict in the marathon contest for the White House.

For the first time in modern American politics the race in both the Democratic and Republican parties appears to be wide open with Hillary Clinton faltering in recent weeks in the face of a challenge from Barack Obama, while Rudy Giuliani and Mitt Romney — who once led the Republican field — have watched aghast as Mike Huckabee has surged to the front.

Yesterday a flurry of potentially important endorsements swirled through the frozen air of the two crucial early voting states of Iowa and New Hampshire.

John McCain, a Republican candidate widely written off after a disastrous summer, received the backing of the independent senator Joe Lieberman, the Democrat vice-presidential nominee in 2000, who said that he was best candidate to lead America “in the fight against terrorism”.

He is now running his presidential campaign on a shoestring budget and spoke inside the public library in Concord before two dozen supporters without the expensive trappings of his better-funded rivals.

On a blustery, sub-freezing day Mr McCain was in an upbeat mood, describing Mr Lieberman's support of him as an “act of courage” and pointing to newspaper endorsements that he hoped would win over New Hampshire's large bloc of independent voters. He still trails Mr Romney by 13 points in the latest poll of New Hampshire, where, among Democrats, Mrs Clinton is shown as edging back ahead of Mr Obama.

A poll yesterday in Iowa, where the state's caucus kicks off the nominating process on January 3, shows Mr Huckabee ahead of Mr Romney by nine points, with Mr Giuliani a further six points behind. Mr Obama leads for the Democrats, nine points ahead of Mrs Clinton and John Edwards.

Mr Romney was still drying his eyes yesterday from a tearful Sunday TV interview when he once again had to defend his Mormon faith. His campaign said yesterday that his claims in the same interview to have received the valuable endorsement of the powerful pro-gun lobby, the National Rifle Association, were false.

Mr Romney was still able to attack Mr Huckabee — who was trying to improve his poor finances by raising money in Beverly Hills yesterday — for fresh criticism of President Bush's foreign policy.

Mr Huckabee was also under fire over a bizarre episode dating back to his time as Arkansas Governor when his teenage son was dismissed as a holiday counsellor amid allegations about the hanging of a stray dog at a Boy Scout camp. The Huckabee campaign was yesterday discomfited by claims of a cover-up in Newsweek.

His fellow Republican Fred Thompson picked up the much sought-after endorsement of the Iowa Republican congressman Steve King yesterday, while Mr Giuliani's campaign was reported to be cancelling advertisements in New Hampshire so that it could focus efforts on later states such as Florida, where his poll lead was being eaten away by Mr Huckabee.

The Republicans, who by this stage are usually uniting around an establishment candidate, are in utter disarray this year with voters indicating strong doubts about almost every one of their five top-tier candidates.

Ron Paul, a sixth Republican candidate standing on a maverick libertarian ticket, is doing his best to make the field even wider and announced yesterday that he had smashed fundraising records for a second time by generating no less than $6million (£3million) on a single day, Sunday.

Mr Obama, on a bus tour of northern Iowan cities, won the backing of the Iowa Democrat congressman Dave Loebsack, giving him the backing of two out of three Iowan Democrats on Capitol Hill. Mr Edwards was expected to be endorsed by Mari Culver, the wife of the Iowa Governor, Chet Culver.

Mrs Clinton, who was endorsed on Sunday by the influential Des Moines Register newspaper, is flying around all 99 Iowan counties in what is inevitably being called a “hilli-copter”. She is now belatedly trying to reintroduce herself to an increasingly sceptical Iowan public with personal testimonials from friends and constituents “talking about the Hillary I know”.

This latest tactic from a campaign riven by internal dispute over recent days is designed to soften an image which is often seen as cold and calculating. On Sunday she stopped at a livestock auction to say: “I know you're going to inspect me. You can look inside my mouth if you want.”

Yesterday she professed to be unconcerned by the tightening of polls in Iowa and New Hampshire, saying: “I just don't pay attention to those snapshots. I've done this a very long time and I never believe that any election is at all predictable, let alone inevitable.”

Mrs Clinton indicated that even if she loses the early contests, the nomination would be decided later when the larger states get to vote and where she continues to have a substantial lead.

THE DEMOCRATS

Hillary Clinton No longer the inevitable or even probable winner. She has to stabilise a shaken campaign and pick up one or two of the early voting states before February 5 — but winning Iowa would make her seem unstoppable once more

Barack Obama His plan is to win Iowa, bounce his way into New Hampshire and then all the way to the White House. But he can still lose momentum as fast as he has gained it and faces a tough couple of weeks

John Edwards Has staked everything on Iowa where he has a formidable ground operation. But even if he wins there, does he have enough of an organisation in New Hampshire and elsewhere to sustain a challenge?

THE REPUBLICANS

Rudy Giuliani Struggling in the early states, he must do enough to stay alive in Iowa and New Hampshire if he is to capitalise on poll leads in Florida and Super Tuesday states. But no one has ever won with such a “big state” strategy

Mike Huckabee Has surged to the top of the polls in most early states. Now faces not only intense scrutiny of his record and weird-looking policy, but also a huge test in building a national organisation to match his new status

Mitt Romney Still leads in New Hampshire having slipped behind in Iowa, has deep pockets and good organisation. But he needs to catch fire with a message that overcomes doubts about his Mormon faith, policy flip-flops and a wooden, paint-by-numbers campaign

John McCain Down-and-out last summer, he could pull off a comeback win in New Hampshire. But, as his 2000 campaign proved, victory in New Hampshire is not enough to secure the nomination while his age, liberal immigration policies and lack of cash still count against him

Fred Thompson At last showing faint signs of life after a desperately disappointing late start to his campaign. He needs to squeeze into the top three in Iowa and hope to win big in his native south

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