In Douglas County, Colorado, lives Lu Busse - mother, grandmother, activist and the original "mama grizzly". Long before Sarah Palin conjured up the image of a mother bear "that rises up on its hind legs when somebody's coming to attack their cubs", Busse had been calling herself "Grizzly Granny Lu" on her blog. "I always said that if we give up on the Republican Party and start a new party, we're going to be the Grizzly Bears," she tells me. "These donkeys and elephants, that's ridiculous. In America, if you're not a grizzly bear, you're not really American."

Busse founded her local 9.12 Project group in April last year, just a month after the Fox News presenter Glenn Beck launched the national project based on nine principles and 12 values (numbers one and two: "America is good" and "I believe in God and He is the centre of my life"). Busse now chairs the statewide coalition of 9.12 groups, and works closely with the Tea Party movement. Locally, female membership is dominant; Busse says that around 60 per cent of the activists she works with are women. It mirrors the national picture. A poll conducted by Quinnipiac University in March this year suggested that 55 per cent of Tea Party sup­porters are female. And they are growing in power. In the past few months, a string of ultra-conservative female candidates, such as Christine O'Donnell in Delaware and Kristi Noem in South Dakota, have won in the Republican primary elections.

Palin calls it a "mom awakening", a movement of newly empowered conservative women who are anti-government, anti-establishment and seeking to destabilise a political system they perceive as elitist and remote. The appeal of candidates such as O'Donnell is their lack of political experience: they are traditional, homely mothers. Yet the ambition of activists such as Busse is huge. She wants to change "the whole direction of the way the country's moving" - and believes she can.

When I ask her if she feels part of a women's movement, Busse reflects for a moment, and then says: "It's not a women's movement in a way that the movement that generated feminism is. This is a movement that wants our country to be the country we grew up in - we want that for our children and our grandchildren. So it gets to our motherly instincts. It's not about women's issues."

It is a telling distinction. For Busse and others like her, feminism is a word laden with alien liberal values, wedded to a time of sexual liberation and immorality. Instead, their bond is motherhood, as reflected in an expanding behind-the-scenes network of activist organisations: As a Mom; Concerned Women for America; Moms for Ohio; Homemakers for America; American Mothers.

Palin gave her "mama grizzly" speech at a breakfast meeting of the Susan B Anthony List in May this year. Founded in 1992 and named after the 19th-century civil rights leader who campaigned for women's suffrage, the List works like an engine room behind conservative female candidates, providing financial backing and mobilising supporters. With 280,000 members, it has funded and campaigned for O'Donnell, Noem and about 25 other candidates across the US. It also has one specific aim, says the group's chair, Marjorie Dannenfelser, which is to "help elect and involve pro-life women in the political project": to end the practice of abortion.

“What we're seeing," Dannenfelser tells me, "is a correction of the term feminist, an editing - women who feel very strongly about the talents and skills and power of women, but who don't feel that abortion is an avenue to that." For Kathleen Blee, a professor of sociology at Pittsburgh University, the idea that women such as Dannenfelser describe themselves as feminists is extraordinary. "It's a terrible distortion," she says. "It strips most of the meaning away from feminism . . . They don't support equal rights, they don't support abortion - you name the feminist issues, they are on the other side." Dannenfelser says that the election races she gets most excited about are those featuring "women running against women where there's a clear contrast between the type of feminism the two candidates represent"; as in, one is pro-life, the other pro-choice. It's
a strange kind of sisterhood.

Conservative feminism in the US is hardly new. One of its early incarnations was the Women's Christian Temperance Union, established in 1880 as part of the temperance movement campaigning for the prohibition of alcohol (a movement in which Susan B Anthony was heavily involved). According to Blee, early rightist women's activism often had a racist tendency. Those involved in the pro-suffrage movement, for example, were galvanised to ensure that white female voters could out­number black men. A number of those women, Blee says, became an influential presence in the Ku Klux Klan, whose membership included at least half a million women at its peak in the 1920s.

Women were also involved in the pro-fascist movements in the Second World War, and in anti-desegregation campaigning during the civil rights movement. But rightist women's movements "exploded", Blee says, with the emergence of an organised Christian right in 1979, the year the pastor Jerry Falwell founded the Moral Majority.

As an evangelical movement that coalesces around issues such as abortion and gay marriage, the Christian right has played a significant role in US politics ever since. The Republican strategist Karl Rove's direct appeal to its base was seen as a deciding factor in George W Bush's re-election in 2004.

The Tea Party has proved to be a magnet to the Christian right, and has been infused by the movement's socially conservative values, even though its original objectives were ex­clusively fiscal. (Busse is typical in citing the bailout of the banks after the 2008 financial crisis as the trigger for her activism.) For Tea Party purists, the infiltration by Christian groups is not necessarily welcome. One activist I spoke to felt their preoccupation with moral issues was potentially divisive, and diluted the Tea Party's central messages around tax and spending. But Dannenfelser sees it differently. "There is so much overlap in the Tea Party movement between economic and social issues that there is really no discontent," she says. "It is simply a matter of emphasis."

For activists such as Dannenfelser, who have been fighting abortion for decades, the events of the past two years have been a perfect storm: the financial crisis, the election of Barack Obama and the consequential birth of the Tea Party have given social and Christian conser­vatives a wave to ride and, in the form of Palin, a ready-made, pro-life, "hockey mom" leader with a direct line to Fox News and, some seem to think, God.

Mum's the word

There is, as yet, no Concerned Women for Britain, or Mums for Basingstoke. Perhaps the closest thing we have to a mass women's movement is Mumsnet. But while the social networking website has political influence - all three party leaders raced to interact with its 1.1 million users before the last election - it is resolutely non-partisan. Its co-founder Justine Roberts tells me she can't imagine the site ever aligning itself with a party or ideology, given the diverse political views held by the mothers who contribute to its discussion forums.

Yet Britain, like America, has a history of conservative women's activism. The British Women's Temperance Association was formed at almost exactly the same time as its US counterpart. With campaigns for sexual purity and chastity, it played a central role in the women's suffrage movement. And Margaret Thatcher (a "heroine" to Palin) is a role model of sorts for British conservative women - although the feminist writer Natasha Walter argues that Thatcher was an anomaly, and one of her own making: "She didn't put in place any policies to encourage equality or to encourage women."

Today, Theresa May is conspicuous as the only woman in a senior cabinet position in the new government. Lower down the ranks, however, there has been a shift. A raft of new female Tory MPs entered parliament at the last election - up from 17 to 49. One, Louise Bag­shawe, chick-lit author and MP for Corby, says this is partly a result of May's efforts to alter the gender balance of the party by starting the Women2Win campaign in 2005. Bagshawe defines herself as a feminist and describes May as the "godmother of a movement".

Like some of her American sisters, Bagshawe is also anti-abortion. "I've never had a problem with being pro-life and a feminist," she says.
“I don't consider them to be at all incompatible." She reveals that she is a member of a prominent US pro-life lobby group, Feminists For Life, and that she admires Sarah Palin. "I watched her acceptance speech at the Republican party conference and it seemed to me that it was a glorious moment, a birth of a new political star." Bagshawe acknowledges that the campaign exposed "various problems" (such as a glaring lack of policy knowledge), but is impressed by the comeback Palin has achieved since the 2008 election, and the power she now wields. "She's a remarkable figure."

Bagshawe's adulation is echoed by one of her colleagues in parliament, the MP for Mid Bedfordshire, Nadine Dorries (who is also pro-life and has campaigned vocally for a reduction in abortion term limits). "I think Sarah Palin is amazing," Dorries says. "I totally admire her." She particularly likes how Palin has spoken up for a certain type of woman - the same women, she believes, who are ignored in Britain today. "Do you know the people who have no voice in this country? Who are never written about, who journalists never talk about? The mums. Mums who decide that they will give up their careers and stay at home and look after their children."

She directs me to a blog post she has just written, "The Invisible Woman", which contains a link to a video of a motivational speech given by an American woman, Nicole Johnson. The central message is one from God to mothers: "You are not invisible to me. No sacrifice is too small for me to notice. I see every cupcake baked, every sequin sewn."

Dorries says she has been inspired by recent events in the US - the primary victories of O'Donnell and others. With a new government in place, she senses a "wind of change" in the political atmosphere in Britain. In the last parliament, she says, it was "very difficult to talk about the family unit, and to talk about mothers and children . . . as the foundation of society, because it was seen as a very unsexy, untrendy thing to do and the opposite of what a woman should be doing". Now, she feels these issues can be discussed.

Her assessment is borne out by Walter, who tells me of a recent meeting she attended with coalition ministers in which they discussed the sexualisation of children. The ministers said they felt it was their duty to provide moral leadership to the country. "That's something I am not comfortable with," Walter says. "But I can see that a Conservative government would think that's where they have to lead."

It is certainly what Dorries thinks. And not only that. Given the sympathetic political climate, she sees an opportunity to mobilise a perceived constituency of ignored, stay-at-home mothers. "I think it's time somebody started to represent those mums," she says.

Not to be dismissed

Since the Tea Party rose up across the US in 2009, a common response to its more extreme factions and candidates has been amusement. Conservative female politicians such as O'Donnell are routinely dismissed, even by leading figures within the Republican Party. Karl Rove recently described O'Donnell's rhetoric as "nutty". Yet the mass appeal of these women is already translating into votes and victories. To discount them is to underestimate their growing power, and also makes for ineffective opposition. As Blee says: "People here do not take women very seriously, they do not take the Tea Party as a whole very seriously, and I think it's clear that's a mistake."

The point on which all the women I spoke to agreed, whatever their shade of politics or feminism, was how often female politicians of all parties and ideologies are patronised. "I wouldn't want to claim Sarah Palin as a sister," Walter says, "but I don't like it when she is despised and trivialised simply for being a woman." And it's not just the Americans. Parliamentarians such as Dorries (nicknamed "Mad Nad") are derided and disregarded as a matter of course.

The "mama grizzlies" are undeterred as they gear up for the midterm elections in November. Dannenfelser is optimistic, pointing out that she has "four strong viable pro-life women who are running [for the Senate] and could win, and three governorships in the same situation". Blee, however, is doubtful about the Tea Party's political longevity. She suggests that the range of views and motivations within the wider movement will make it hard to sustain. Electoral success in the midterms, she believes, might precipitate a collapse by exposing factions and splits.

Nonetheless, uniting all these women and issues is one woman, a de facto leader who appears to be on her way to the very top. "The prospect of Sarah Palin as a presidential candidate is not worth discounting," Blee says.

But could she win the presidency? "Yes, as crazy as that is." As Lu Busse says, laughing, just before she hangs up the phone: "The folks in Washington ought to know that they're in real trouble . . . They've got the women after them now."

Sophie Elmhirst is assistant editor of the New Statesman.