If, as the polls suggest, the John McCain-Sarah Palin ticket is about to fall beneath Barack Obama's Democrat juggernaut, that may not mean Mrs Palin heads home to Alaska never to be heard from again.

American political history is littered with losing vice-presidential candidates who have sunk without trace, but Mrs Palin is unlikely to be one of them. Just as this is no ordinary election, the Alaska governor is no ordinary candidate.

She has emerged in spectacular fashion just as the Republicans face the prospect of a leadership vacuum should Senator McCain lose.

At 72, he is the oldest-ever presidential candidate and, in terms of his future, this election represents closing time at the Last Chance Saloon.

A self-styled maverick, Senator McCain has always been on the fringes of the party establishment and, even if he were younger, would not be an automatic choice to lead the party into opposition.

'If we lose, the Republican Party is going to face a really tough period of soul-searching after the Bush years,' said one party veteran.

'The state of the economy will also be forcing us to consider exactly what we stand for ... and all of this will take place at a time when we have very few stars out there.'

Rightly or wrongly, one of those stars is likely to be Sarah Palin. She has a closer eye on the modern Republican base than her patron, being far more socially conservative and religiously evangelical.

After one month of controversy and mockery, she also has name recognition - an increasingly important commodity in modern American politics.

And her ambition is all too clear. Aged just 44, it has carried her from the mayoralty of the 8,000-strong Alaskan town of Wasilla two years ago to the governorship of the state, taking on entrenched interests in her own party along the way.

Early on, advisers were telling her that energy policy - one subject she has a solid grasp of - was a key to the national stage. 'I didn't even blink,' she said when asked if it was a tough decision to say 'yes' when Senator McCain called.

She has also shown her desire to fight over the past month, leading the charge after the McCain campaign decided to get rough last week. Her claims that Senator Obama has been 'palling around with terrorists' - a reference to his ties to a Chicago education professor and 1960s radical - and is 'not an American like you or I' have been some of the most inflammatory remarks of the campaign.

The McCain camp is now backing away from such attacks, apparently having registered polls that show they have done nothing to halt Senator Obama's well-funded drive into Republican strongholds.

Quite how Mrs Palin will handle being reined in is far from clear. Well-placed campaign sources note she has wanted Senator McCain to get even tougher with Senator Obama to claw their way back into contention. She also complained publicly about his decision to abandon campaigning in Michigan, an important mid-western state, to focus resources on other swing states.

Her speaking style, too, betrays a tone that galvanises the Republican base. She avoids the nuance of Senator McCain, shutting down potential points of contention with appeals to patriotism and a claim to be forward thinking.

As her opponents question Iraq or Afghanistan, Mrs Palin declares 'that's not what our troops want to hear right now'. Or when her opponents reflect on eight blunder-filled Bush years, it's 'there you go again, pointing backwards ... I want to focus on solutions and the future'.

It is the brutally effective style of Mr Bush, who won two elections despite intense debate about his skills and qualifications, in part by keeping his messages simple and shunning nuance. It is the politics of sheer self-belief.

She seldom mentions Mr Bush, yet also echoes Senator McCain's appeal that she is determined to 'fix Washington'.

She loves to talk of American 'exceptionalism' and to quote former president Ronald Reagan's vision of her country as a 'shining city on a hill'. She may be on her way, but she hasn't reached it yet.