I won't run for White House, says Sarah Palin as she ends speculation

Ending the longest tease in American politics, Sarah Palin announced last night that she will not seek the Republican nomination for President.

The former Alaska Governor, plucked from relative obscurity to be the party's 2008 vice-presidential nominee, said that she and her family had decided not to seek the White House next year, despite clear evidence that Republican voters are yet to alight on a favourite candidate.

In a letter to her supporters, she said: "As always, my family comes first and obviously Todd [her husband] and I put great consideration into family life before making this decision. When we serve, we devote ourselves to god, family and country. My decision maintains this order."

As one of the standard-bearers of the Tea party insurgency within the Republican party, Ms Palin has electrified audiences of the faithful wherever she appears, but in truth her political star had appeared to wane as voters tired of the will-she-won't-she antics of the past few months.

The former governor has never set up a professional campaign staff, yet kept teasing interviewers with hints that she could be persuaded to seek the nomination, and she was a conspicuous presence in the early primary states – even to the point of upstaging frontrunner Mitt Romney on the day he formally announced his campaign. On the weekend of the Iowa straw poll in August – won by another now-faded star of the Tea party, Michele Bachmann – Ms Palin could be found in the state with her election battlebus-style "One Nation" coach, emblazoned with the Liberty Bell and script from the Constitution.

Pundits, though, have long suspected that Ms Palin prefers the attractions – often lucrative attractions – of the private sector, where she has fronted wildlife documentaries filmed in Alaska and pushed her political message through paid-for speaking engagements and a well-remunerated gig as a contributor to Rupert Murdoch's Fox News cable channel.

Last month, she mused aloud on Fox about the presidency: "Is a title worth it? Does a title shackle a person?"

That was widely derided at the time, but she repeated the idea of the presidency as a mere "title" in the letter explaining her decision not to run. "I believe that at this time I can be more effective in a decisive role to help elect other true public servants to office – from the nation's governors to Congressional seats and the Presidency. By working together we can bring this country back – and as I've always said, one doesn't need a title to help do it."

She said that she expected to campaign on behalf of the eventual Republican nominee, though declined to throw her weight behind any of the declared candidates at this stage. Her non-appearance in the race in theory ought to boost Rick Perry, the Texas Governor who has strong appeal on the right, but his shaky performance so far has raised doubts about his candidacy. Mr Romney beats him in national polls of Republicans, but only by a slender margin, and many party donors and supporters are clamouring for other candidates to emerge.

Ms Palin's exit comes the day after New Jersey Governor Chris Christie said he would not run, despite being urged repeatedly to do so.