John McCain’s campaign is putting pressure on the organisers of the vice-presidential debate tomorrow night to go easy on Sarah Palin amid growing alarm that faltering performances in recent days have made her an object of public ridicule.

Yesterday she was at Mr McCain’s ranch in Arizona with some of his most senior advisers, undergoing an intensive programme of preparation for the televised clash with Joe Biden, her Democratic rival.

Only a fortnight ago the Governor of Alaska was seen as a potential saviour of the Republican party, having reinvigorated a previously torpid conservative base with an electrifying speech at the convention in St Paul.

However, after initially being kept away from the media, a series of gaffes on the campaign trail and an embarrassing interview with CBS have transformed her into a potential liability for Mr McCain.

Nancy Pfotenhauer, a senior campaign strategist for Mr McCain, has asked for fewer questions than might be expected on foreign policy in the debate. Pointing out that Mr Biden – chairman of the Senate Committee on Foreign Relations – would have an advantage on such issues, she said that the clash should at least be evenly balanced with domestic concerns. “The moderators will have some questions to answer themselves if they do go so heavy [on] foreign policy.”

In her interview on CBS, Mrs Palin struggled to defend a claim that the proximity of her state meant she was an expert on Russia, was then unable to answer questions about Mr McCain’s achievements in regulating big business and suggested that the military had already won the war in Iraq.

The comedy show Saturday Night Live parodied her as asking if she could “phone a friend” when faced with one question. Some of the biggest laughs, however, came when Tina Fey, the impersonator, used phrases that closely resembled Mrs Palin’s own ramblings.

CBS is said to be planning to broadcast further segments of the interview in which she was apparently unable to name any Supreme Court judgments other than the Roe vs Wade ruling on abortion. An aide said that there was no fumbling on this question, merely silence.

Some conservative commentators have even suggested she be replaced. Kathleen Parker, writing for the National Review, said that her “cringe reflex is exhausted” after watching Mrs Palin exposed so badly. She wrote: “Like so many women, I’ve been pulling for Palin, wishing her the best, hoping she will perform brilliantly. I’ve also noticed that I watch her interviews with the held breath of an anxious parent, my finger poised over the mute button in case it gets too painful. Unfortunately, it often does.”

Mitt Romney, who narrowly missed becoming the vice-presidential nominee, is among those who think Mrs Palin has been overly schooled – losing spontaneity and confidence as a result. “I think they’d be a lot wiser to let Sarah Palin be Sarah Palin,” he said. Advisers said that many people would be appalled at the sneering towards her, and opponents patronised Mrs Palin at their peril. “She continues to be a huge asset who speaks directly to the middle American voter that the media so often ignore,” one source said.

Privately, strategists said that at least expectations have been lowered for the debate. Mrs Palin breezily insisted that she looked forward to going into battle with Mr Biden, who seemed “pretty doggone confident – like he’s sure he’s going to win”. She emphasised how long he had been a Washington insider, saying: “I’ve been hearing about his Senate speeches since I was in, like, second grade.”

Mr McCain has little option but to stick up for her and declare his pride in his vice-presidential pick. In a joint interview with her he defended comments made at the weekend in which she had once more wandered off-message by supporting cross-border attacks from Afghanistan into Pakistan, like Barack Obama had.

Asked what she had learnt from the experience, Mrs Palin replied: “That this is all about ‘gotcha’ journalism. A lot of it is – but that’s OK, too.”

Borderline humour

Mrs Palin in her own words:

‘Alaska has a very narrow maritime border between a foreign country, Russia, and, on our other side, the land-boundary that we have with Canada . . . As Putin rears his head and comes into the air space of the United States of America, where do they go? It's Alaska. It's just right over the border. It is from Alaska that we send those out to make sure that an eye is being kept on this very powerful nation, Russia, because they are right there . . . right next to our state.’

Saturday Night Live's Tina Fey as Mrs Palin:

‘You got Alaska here, this right here is water, and this is Russia. So, we keep an eye on them. Every morning, when Alaskans wake up, one of the first things they do is look outside to see if there are any Russians hanging around. And if there are, you ask, ‘What are you doing here?’ and if they can’t give a reason, it’s our responsibility to say, “Shoo! Get back over there”!’

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