With all due respect to my esteemed colleague Jonathan Freedland, I feel compelled to contest his theory that the belle of this year's Republican ball will be back in the presidential chase come 2012.

A victory for John McCain would certainly give Palin the chance to rehabilitate her approval ratings and consolidate her appeal to the conservative base in preparation for a future presidential run. But if Barack Obama becomes president next year – and it's a bigger assumption than most liberals would like to think right now – Palin is going to have a devil of a time making a viable bid for the White House.

The first factor holding her back is the same enemy that Palin often decries before her rapt audiences: the media. Every publication from the New Yorker to Field and Stream magazine descended on rural Wasilla, Alaska after Palin joined the Republican ticket last month, and the resulting crush of damning press created a string of ready-made attack adverts for any possible opponent in 2012.

Imagine if John Edwards, the 2004 Democratic vice-presidential nominee, had emerged victorious as his party's nominee this year.

Even if Edwards's infidelity had not become public, Republicans would be subjecting him to a daily re-litigation of the same battles that brought down the Kerry-Edwards ticket four years ago. His campaign would be watched hawkishly for the slightest hint of a reversal on the issues – and so would Palin's in 2012.

Given that the Alaska governor can barely keep her positions straight over a period of weeks on topics as sensitive as military action inside Pakistan and judicial refinancing of mortgages, you'd better believe that Democrats would salivate at the chance to fact-check her four years from now. Not to mention, operatives will be watching to see whether Palin's pricey designer clothes show up at the Salvation Army after the election.

The second drag on Palin's political future is her state. Yes, Alaska is certainly remote and offers scant opportunities for national political exposure. But most importantly, it also lacks a substantial fundraising base from which Palin can extract the cold, hard cash necessary to run for president four years from now.

Her best chance to build a network over the next four years as governor is courting the major oil companies. But Palin was correct in noting that her independent-minded approach to the Alaska natural gas pipeline turned off Exxon and the other energy giants.

Sarah Barracuda is certain to remain in the good graces of Bill Kristol, Fred Barnes and other A-list conservative pundits who are enthralled by her stage presence. (Peggy Noonan, as it happens, is far from a Palin fan these days.)

Still, even if Kristol & Co can give her entrée to the Washington power elite – something tells me McCain won't be in the mood to share after a loss this year – Palin is bound to watch her approval ratings suffer in Alaska as she openly plans another run at the White House.

On the subject of approval ratings, they happen to be the third factor imperilling Palin's presidential future. Polling is generally untrustworthy on the details, but Palin's numbers paint a distressing picture: the more voters get to know her, the less they like her.

After Palin stormed onto the national stage with her combative convention speech last month, she boasted a 54% positive rating. Five weeks later, her approval rating had fallen to 44%, compared with 60% for Democratic No 2 Joe Biden.

Voter perceptions of Palin also have suffered back in Alaska, albeit on a smaller scale. Does anyone think the bespectacled governor will be able to return home quietly for two years of fighting environmental regulations? Palin had better start getting used to the pesky media tracking her every move on the local level, particularly her clashes with Alaska critics Andree McLeod, Andrew Halcro and Anne Kilkenny.

Four years from now, Palin is unlikely to be enjoying the 80%-plus approval that gilded her emergence this autumn, especially if she faces a difficult re-election fight in 2010.

That brings me to the fourth and final reason that Palin 2012 is less of a sure thing than Freedland and others believe. Palin's term expires in 2010, the same month that Republican Lisa Murkowski must defend her Senate seat.

Having spectacularly unseated Murkowski's father, Frank, in order to become governor, Palin may well decide that knocking off another Murkowski is her best path to broader power. The Senate would be the best perch for Palin to keep an eye on a potential President Obama if she wants to run in 2012 – which would surely depend on how vulnerable Obama is to a successful challenge by that point.

But wait: Palin would first have to win that Senate seat. And although she energises the conservative base now, she does so largely through prepared talking points, depicting Obama as a "pal" of terrorists and McCain as "the only man" who can defend America. The next several years will test her ability to delve into the more substantive critiques that are required of both Senate and presidential candidates.

Before Palin and her fans in the media-political-industrial complex get psyched about a 2012 run, she'd do well to bone up on policy. A good place to start might be learning that the vice-president doesn't actually rule over the Senate.