You hear it on the campaign trail everywhere, but now a NBC/Wall Street Journal poll appears to confirm it. No longer a net asset to the Republican ticket, Sarah Palin may in fact be weighing John McCain down.

Those voters crucial to the final outcome – the undecideds and independents – don't quite like her, think her selection was cynical and political and cannot imagine her ever being president. And to make matters worse, details emerged yesterday of the Republican Party splurging $150,000 (£92,000) since Mrs Palin became Mr McCain's running-mate to revamp her wardrobe. Lipstick and Armani on a hockey mom sounds fine, but at that kind of cost? After "troopergate" in Alaska, another mini-scandal attached to Mrs Palin is not what is needed.

The Republican Party did not dispute the wardrobe findings of the US website Politico, moreover. By perusing the campaign's financial disclosures for September, the site found that Mrs Palin's fashion expenditure included almost $50,000 doled out at branches of Saks Fifth Avenue in St Louis and New York, as well as more than $75,000 on clothes at high-end Neiman Marcus in Minneapolis, the host city for the Republican Convention. "With all of the important issues facing the country right now, it's remarkable that we're spending time talking about pantsuits and blouses," said a Palin spokeswoman, Tracey Schmitt. "It was always the intent that the clothing goes to a charitable purpose after the campaign."

Ms Palin, of course, has attracted a lot of favourable comment for her dress sense. It has certainly helped her get into the pages of magazines such as People. But questions may be asked whether, in purchasing so many fancy outfits for her – for husband Todd and possibly even for Trig the baby – the campaign may have violated federal election laws governing the use of campaign cash for gifts. Her surprise arrival on the Republican ticket at the end of August initially electrified the Republican base and gave what might have been a dour party convention in Minneapolis-St Paul a shot of adrenalin. That was a good thing, but the question was always this: would she tear independents and former Hillary Clinton supporters away from Barack Obama?

The latest NBC poll is shocking because for the first time, Mrs Palin is seen with a net negative favourability rating among voters, while a majority – 55 per cent – said she would not be qualified to serve as president should anything happen to the anything-but-youthful Senator McCain. Indeed, questions about her qualifications emerged in the NBC poll as the biggest single concern voters have about the McCain ticket.

"What's their problem?" an exasperated Mr McCain asked after hearing on the Don Imus radio show that even some Republicans disapprove of his running-mate. "She's the most qualified of anyone recently who has run for vice-president, to tell you the truth... I'm frankly entertained at the elitist attitude towards a person who is a proven leader."

The NBC poll also put Mr McCain behind by 10 points nationally among registered voters. However, private concerns in the Obama camp that the race may be tightening appeared to be bac ked by a new Associated Press poll that separated the two candidates by a mere one percentage point. Mr Obama was on 44 per cent to Mr McCain's 43 among likely voters.

Mrs Palin, with her folksy, attack-dog stumping style, continues to draw large crowds and her growing number of interviews shows she has freed herself from the protective cocoon that was spun around her in the weeks straight after her nomination.

But exposure brings new perils for Mrs Palin, who was back in gaffe territory yesterday after responding to an eight-year-old on a Colorado television station asking what it is exactly that a vice-president does. Not for the first time, she responded that the Veep runs the US Senate, which is more overblown than the federal deficit. A vice-president is on hand to break a tie-break vote in the Senate, but that is all.

The kid was called Brandon and in answering him about the Veep's duties, the Governor really rammed the mistake home. "They're in charge of the United States Senate, so if they want to they can really get in there with the senators and make a lot of good policy changes that will make life better for Brandon and his family and his classroom."

And on CNN on Tuesday, Mrs Palin had to apologise for implying on the trail that some parts of the US are more "American" than others. "We believe that the best of America is in these small towns that we get to visit, and in these wonderful little pockets of what I call the real America, being here with all of you hard-working, very patriotic, very pro-America areas of this great nation," she had told a crowd (in a small town) in North Carolina last week. Asked if that wasn't a bit offensive to those "other parts" of the country, she told CNN: "If that's the way it has come across, I apologise."

Palin's shopping list: $150,000 well spent?

* Saks Fifth Avenue: $49,425.74.

* Neiman Marcus: $75,062.63

* Macy's: $9,447.71

* Barneys New York: $789.72

* Bloomingdales: $5,102.71

* Hair and make-up: $4,716.49

Expenditure comes to over $150,000. That's $2,500 every day. Or four times the salary of your average 'Joe the plumber'