BOSTON - MOCKED by comedians, derided by prominent conservatives and reeling from flustered interviews with national media, Mrs Sarah Palin is proving a risky gamble in Republican John McCain's quest for the White House.

'Palin is Ready? Please' a headline in Newsweek said this week of the moose-hunting Alaska governor and vice-presidential candidate, capping a turbulent week in which Mrs Palin's fitness for the job came under growing scrutiny.

'Sarah Palin is utterly unqualified to be vice-president,' Newsweek International Editor Fareed Zakaria wrote.

'She is a feisty, charismatic politician who has done some good things in Alaska. But she has never spent a day thinking about any important national or international issue, and this is a hell of a time to start,' he said.

The column could be dismissed as one of hundreds of biting news stories in the hard-fought race between Mr McCain and Democrat Barack Obama, with less than six weeks before the Nov 4 presidential election.

But it follows a whirlwind of criticism and ridicule from Republicans and Democrats alike since interviews with CBS news anchor Katie Couric, Fox News' Sean Hannity and ABC News' Charles Gibson that raise question over her nomination and dealings with the media.

History shows most Americans vote for presidents, not vice-presidents and Mrs Palin's folksy appeal energises far larger crowds than those drawn to gaffe-prone Democratic vice-presidential nominee Joe Biden, whom she debates on Thursday.

But the governor's troubles are piling up - from a stubborn investigation into charges that as governor she abused her power by firing a public safety commissioner to her latest stumbles with the media.

Conservative columnist Kathleen Parker, an early Palin supporter, on Friday bluntly called on Mrs Palin to step down to 'save McCain, her party, and the country she loves'.

'Quick study or not, she doesn't know enough about economics and foreign policy to make Americans comfortable with a President Palin, should conditions warrant her promotion,' Ms Parker wrote in the conservative National Review.

Mrs Palin could withdraw from the race for personal reasons such as wanting to spend more time with her newborn, added Ms Parker, who in September rallied behind Mrs Palin for showing 'strength, conviction, determination' and confidence.

'Embarrassing'
The 44-year-old self-described hockey mom's image of homespun authenticity, which boosted Mr McCain last month with a leap in support among white women, has been replaced by a less flattering image as a political neophyte and butt of jokes.

The popular TV sketch comedy show Saturday Night Live mocked Mrs Palin's assertion that governing Alaska gives her foreign policy experience because of its geographic proximity to Russia.

Late-night television host David Letterman said Mrs Palin's meetings with world leaders at the United Nations looked like 'take your daughter to work day'.

Until last Tuesday, Mrs Palin, who would be a heartbeat away from the presidency if 72-year-old McCain were to win the election, had never met a foreign leader.

Conservative New York Times columnist David Brooks called her candidacy 'embarrassing'. But political analysts say she remains a powerful force in Mr McCain's campaign despite her bad reviews.

They cite her proven ability to rally evangelical Christians and connect with other socially conservative Republicans, whose grass-roots muscle could propel Mr McCain in crucial states.

Expectations for Thursday's debate are also now so low that Mrs Palin's chances of looking good have improved, they add.

'The more interviews she does, the more nervous not just moderates get, but some conservative Republicans get. But thus far they still generally see her as a benefit,' said Mr Julian Zelizer, a professor of politics at Princeton University.

'They didn't pick her to please David Brooks. They picked her to please conservative activists. If anything, the attacks on her from Saturday Night Live or from New York Times columnists will only fuel some of the resentment and excitement about her. In that respect she is still a plus for McCain.'

Mr McCain stuck by Mrs Palin on Monday, telling a crowd in Ohio that 'she will be my partner in reforming everything that's broken in Washington.'

On Sunday, he defended her after she contradicted his policy against talking publicly about attacking terrorist targets in Pakistan.

Former Republican presidential candidate Mitt Romney, once touted as a possible McCain running-mate, questioned the campaign's strategy of restricting Palin's media exposure.

'Holding Sarah Palin to just three interviews and microscopically focusing on each interview I think has been a mistake,' Mr Romney said on MSNBC television.

'I think they'd be a lot wiser to let Sarah Palin be Sarah Palin. Let her talk to the media, let her talk to people.' -- REUTERS