Congresswoman will come under scrutiny about hardline politics. But will she be able to reach beyond her Tea Party base?

Mary Cecconi is the only Democrat to have beaten Michele Bachmann, the rising star of the Republican right, in a popular election. "It's my claim to fame!" she laughs.

Her victory came in a race in 1999 for a seat on the school board of Stillwater, Minnesota, a tiny, picturesque river town on the banks of the St Croix river. Bachmann – then known locally as a conservative education activist – had unexpectedly run as part of a slate of rightwing Republicans. The move politicised what had previously been a non-partisan affair. It failed. Cecconi, the incumbent, held her position.

It was a minuscule electoral footnote yet it saw the political birth of a woman who just 12 years later is running for president and electrifying the radical right wing of the party.

Bachmann, who announced her White House run last week, and then shone in the first major Republican debate, is eclipsing Sarah Palin as the new darling of the Tea Party. She is an evangelical whose husband runs a controversial Christian counselling service. She is a Minnesota congresswoman who has vowed to repeal healthcare reform and lambasts Barack Obama as a socialist. Like Palin, she makes political capital of her role as a mother to a large family: five children of her own and more than 20 foster kids. She is also a glamorous woman in a party that is frequently dominated by older white men.

Yet her remarkable story began with that Stillwater race and Cecconi, now head of a parental lobbying group for schools in Minnesota, is not the only person to remember it. Joan Beaver, a now retired Stillwater high school teacher, recalled the election as heralding a shift in the town away from smalltown moderate Republicanism towards more extreme rightwing thought. "The town changed," she said, noting that the shift occurred after the development of suburban housing estates and an influx of wealthy newcomers.

Bachmann was part of the influx. She was born in Iowa, although the family moved to Minnesota when she was young. After a divorce, her mother remarried and Bachmann spent her childhood in a family of working-class Democrats. The real change came during adolescence, when at 16 she became "born again". She went on to study law at the religious Oral Roberts University, which taught a biblical worldview alongside its legal classes.

By the time Bachmann and her husband, Marcus, arrived in Stillwater with their burgeoning family they were staunch members of the religious right. She home-schooled her own children, but by law had to enrol her foster children into local public schools. It was that experience – she saw the state curriculum as too liberal and politically correct – that led to her becoming involved in educational activism, and ultimately politics.

Still, to Beaver it seems strange to see the Bachmann she knew from Stillwater school politics striding across the American political stage with officially declared ambitions to capture the Oval Office and become the most powerful woman in the world. "She has more perseverance and staying power than anyone expected," Beaver said.

Many on the American left see Bachmann's presidential ambitions as little more than a joke: the punchline to a gag about how far right the Republican party has drifted. She is mocked and lampooned by those who expect her to fail. But not all of her opponents in Stillwater are joining in that ridicule.

Cecconi is certainly not. She recalls going to an education meeting only two days after beating Bachmann in 1999. Bachmann was supposed to be playing second fiddle to a speech by education campaigner Michael Chapman. But instead she had become the main attraction: "She was amazing. She held the room in her hand."

A year later Bachmann would run for – and win – a state senate seat. Shortly after that she would run for the US Congress in the sprawling district of which Stillwater is a part. She would emerge victorious from that, too. Now she is running for the White House. Cecconi has a warning for those mocking her: "She has got as far as she has by people underestimating her. I am not going to underestimate her."

Even Bachmann's admirers, however, sometimes confess that her passionate style of ultra-rightwing politics has its drawbacks. "It is very attractive to some folks, and she certainly does not hesitate to say what she thinks. But that can upset others," said Edwin Cain, a Stillwater-based lobbyist who has worked frequently with Bachmann.

Indeed, it is not hard to find Bachmann critics, even among Republican supporters in the town. Though she makes her home here – in a million-dollar house on an upmarket estate near the golf course – this is not automatically Bachmann territory. The town is prosperous and thrives on a tourist economy; Main Street is packed with bistros and bars and represents a slice of urban city life with a hint of liberal values. Preston Norris, who works in a bar, voted for Bachmann for Congress but will not do so for the presidency. "She has some views that are just too much for that office," he said bluntly.

It is not hard to see what those views are. Bachmann's criticism of homosexuality is open and brutal. She has led the charge against gay marriage, even at the cost of a once-close relationship with a lesbian stepsister. In 2004 Bachmann said of gay people: "It's a very sad life. It's part of Satan, I think, to say that this is gay. It's anything but gay."

She is on record as viewing homosexuality as a "disorder" or a "sexual dysfunction" and is a staunchly anti-abortion Christian conservative. She believes Obama is "the final leap to socialism" in America, and has accused him of wanting to set up youth indoctrination camps for teenagers.

She has called for investigations into fellow congressional politicians to see if they are "anti-American". She once claimed to know of a plan to give up half of Iraq to Iran. She is against raising America's debt ceiling for running up its deficit, and wants to repeal healthcare reform in its entirety.

She is a firm sceptic on the dangers of global warming. She once introduced a resolution seeking to prevent the dollar being replaced by a foreign currency, despite the fact that such a move is already illegal. She has called the Environmental Protection Agency a "job-killing" organisation.

Such extremism can lead to some very odd ideological bedfellows. Away from Stillwater, in the rural hinterland of Bachmann's vast congressional district, she is more popular. Here, in a landscape of deeply religious small towns and rolling farms, Bachmann's support is solid. In Buffalo, a small community beside a lake of the same name, one Bachmann supporter was delighted she was running. "I think it's great! She can win and I have found the president very disappointing," said one elderly woman who declined to give her name. Asked what was most disappointing about Obama, the woman said: "He has not been honest about being a Muslim."

Such beliefs are unusual, but not exactly unknown in these parts. Not far from Buffalo lies the town of Annandale, which acts as the base for a rightwing Christian ministry called You Can Run But You Cannot Hide. Led by the drummer of nu-metal band Junkyard Prophet, Bradlee Dean, the ministry has made its name by denying Obama's Christianity and also promoting slurs against gay people, accusing them of child abuse and even once suggesting they be executed.

Yet Bachmann herself has headlined a fundraising gala for Dean and his ministry. That sort of thing has so far passed under the radar of most American media, but seasoned Bachmann-watchers, such as Stillwater writer Karl Bremer, whose Ripple in Stillwater blog has chronicled Bachmann's career, believe that will not last for long now: "She has to soften her image. But her image is already on the table. She is in the big leagues now. It is not just a little congressional race."

Bremer believes Bachmann's politics and career are about to get the sort of scrutiny they have long deserved. Indeed, he has already chronicled much of it on his blog. "She has got plenty of skeletons in her closet," he said.

One of those skeletons could be her relationship with Frank Vennes, a man who served time in jail for cocaine distribution and money-laundering after being convicted in 1987. After his release, and apparently after finding God while in prison, Vennes became a friend of Bachmann and a big campaign donor for her elections. However, Vennes has recently been indicted on charges stemming from a Ponzi scheme and could end up behind bars again.

That is a juicy story. As are Bachmann's links to the mysterious "Bobby Charles Thompson", who disappeared after the collapse of his apparently fraudulent fundraising organisation, which had been portrayed as a navy veterans' group. Arrest warrants have now been issued for Thompson, whose real identity is not known. But what is known is that Thompson's group donated campaign funds to Bachmann.

Then there is the issue of the Bachmann family farm in Wisconsin. The large rural property has been the recipient of considerable government largesse in the form of agricultural subsidies, despite the fact that Bachmann is a vociferous critic of government handouts. Yet Bremer's blog has reported that the farm has reaped the Bachmanns about $154,000 of government cash since 2001. That is obviously not illegal but – given Bachmann's virulent dislike of state welfare – it could make for some interesting headlines.

Finally, there are bizarre incidents such as the one in 2005 when Bachmann accused two lesbians of trying to lock her in a lavatory and keep her prisoner. The women claimed they were just trying to talk to her about her anti-gay beliefs, but Bachmann went to the police. However, the authorities dismissed her claims. "Both women simply wanted to discuss certain issues further with Ms Bachmann," wrote the county attorney, who declined to press the matter.

To her supporters – and there are many of them – such incidents do not matter. They are either irrelevant or part of the media plot against her. "The media beat up on her. I don't know why," said Lee Bohlsen, chairwoman of the Republican party of Washington county, in which Stillwater lies. Bohlsen is an enthusiastic fan, praising Bachmann's attention to detail and warm personality. "I definitely think she can win. She is unwavering and she has a very strong character," she said.

Indeed, there is no doubting Bachmann's political talents. She ticks all the same boxes as Palin but has a more polished image, even more conservative credentials, and a family and religious outlook that makes Palin look positively liberal. She also has a prodigious, widely admired work ethic and a fierce sense of mission.

"She is absolutely hard-driving and passionate, but that does not make her unpleasant to work with," said Karen Effrem, a conservative education activist who has worked with her. "It makes her a dynamo. I'm pleased she is running."

Reconciling the liberal and conservative visions of Bachmann is impossible. Her detractors and supporters inhabit different worlds. But it has led to speculation that Bachmann might privately not believe all she says in public: that her ambition is simply to bask in the spotlight.

Perhaps, like Palin, she may have more of an eye on realising her value on the lucrative TV talk show circuit than on winning a political race.

Bremer is unsure of the theory and not keen to test it. "Does she believe what she says? Or is it just a road to success?" he said. "I don't know the answer to that – but I do think she should be stopped."