It seems only yesterday that Hillary Clinton was battling against Barack Obama for the Democratic presidential nomination. But when she hits the campaign trail in Florida tomorrow Clinton’s target will be Sarah Palin, a new threat to her ambition to be the first woman elected to the White House.

Clinton lost no time, attacking Palin moments after John McCain delivered his presidential acceptance speech in St Paul, Minnesota, last week. Reporters’ BlackBerrys buzzed with her verdict. “No way, no how, no McCain-Palin,” she said.

Officially, Clinton will not go head-to-head with Palin, a self-proclaimed hockey mom and “pitbull in lipstick”.

The Obama camp wants to keep the focus on McCain’s supposed continuation of the Bush years and his skimpy policies for reviving the economy and improving healthcare, rather than on his running mate.

Nor does Clinton want to appear ungenerous to the Republicans’ first female vice-presidential candidate, even if she does resent Palin’s startling emergence.

A Clinton insider, said: “We’re not going to be anybody’s attack dog against Sarah Palin.” The New York senator, 60, knows, however, that Palin represents the biggest obstacle to Democratic victory in November.

A prominent Democratic strategist, Tad Devine, said: “The strategic imperative right now is to do something about Palin and prevent her cutting through the race. She is practising the same slash and burn politics of division of the Bush years. Hillary Clinton can make the charge that Governor Palin represents the far right.”

Palin has taken aim squarely at the 18m voters who preferred Clinton to Obama during the primary campaign. It is a delicate mission for the New York senator to persuade them, after all her harsh words, that Obama is the right candidate for president.

But attacking Palin represents an even more slippery challenge for Obama. At a fundraiser where diners paid $30,800 (£17,400) per plate at the house of the rock star Jon Bon Jovi on Friday – not the best place to compete with a frontier woman – he said: “We won’t be bullied, we’re not going to be smeared, we’re not going to be lied about. I don’t believe in coming second.”

For that he needs Clinton’s help more than he ever thought possible. Just before Palin’s selection, David Plouffe, Obama’s astute campaign manager, looked at the electoral map of America and declared the national polls less important than the 18 battleground states where Obama had the ground troops, enthusiasm and money to win.

Palin’s emergence has upset those calculations and forced the Obama campaign for the first time to reexamine its extraordinarily successful campaign tactics. Obama now has a great need to drive up voter turnout among black people and the young, while staunching defections to McCain from blue-collar workers and women.

Clinton has been asked to concentrate on the working-class districts of Ohio, Pennsylvania and Michigan, where Palin will be competing fiercely for votes, and Florida, where women and Jewish voters may reject the Alaska governor’s Christian, conservative, anti-abortion message.

Clinton, who has lived through the women’s movement, intends to frame the race in terms of a double-barrelled McCain-Palin threat to issues that women care about such as the right to an abortion, equal pay and universal healthcare, according to the Florida congresswoman Debbie Wasserman Schultz.

As such, she will be joining the roster of prominent women deployed by Obama to such good effect against Clinton herself during the primary campaign. Politicians such as Kathleen Sebelius, the governor of Kansas, Claire McCaskill, the Missouri senator, and Janet Napolitano, the governor of Arizona, have made the case that women could in good conscience vote for Obama rather than Clinton.

Now they are using the same tactics against Palin. Sebelius regards herself as every bit as authentically all-American as the governor of Alaska.

“I live in the American heartland. I don’t know of any mayor in any small town in Kansas who hires a lobbyist and goes after earmarks [congressional funding for projects] the way Sarah Palin did,” she said. If Clinton is uncertain about going for Palin’s jugular, she may like to recall the words of a woman delegate at the Republican convention who described Palin as “more of a woman than Hillary and more of a man than Hillary”.

If Clinton fails to stop her now, she could get trampled.

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