It didn’t matter that she was a junior state senator. It didn’t matter that she was in the political minority. It didn’t even matter that Minnesota already had a law on the books against same-sex marriage.

Michele Bachmann crusaded to take it a step further and have a ban on such unions written into the state’s Constitution.

She fired up conservative followers. She clashed with social liberals and gay leaders, who were infuriated by her description of homosexuality as a sad life of despair and her musing that Satan must have had a part in creating the word gay.

In the vitriol of those days, Bachmann once moved her children out of their home in Stillwater, Minn., worried for their safety, she said.

“I was public enemy number one,” she recalled recently.

But that didn’t sway her. Nor did the quiet distress of her stepsister Helen LaFave, who is four years younger than Bachmann and grew up admiring her. LaFave had been in a committed lesbian relationship for 18 years, and it pained her that Bachmann was leading the charge to make it impossible for her and her partner to marry. She had twice written her stepsister letters that went unanswered.

“It’s been very hurtful,” LaFave, who grants few interviews, said last month. “It affects me and it affects my relationship and it affects my partner. There are so many other issues that a person could champion in public life.”

In 2006, Bachmann walked into a tense hearing room in the state Capitol in St. Paul for a parsing of her proposal. There, in a crowd of activists, academics and religious leaders, were familiar faces: LaFave, her partner and a small group of relatives supporting them.

LaFave wasn’t seeking a confrontation. She wanted to be a visual reminder that real people like her and her partner would be affected. To plant a seed of doubt in Bachmann about what she was doing.

She caught her stepsister’s eye. But as the hearing ended and word trickled out about LaFave’s presence, both women were besieged by reporters.

They never talked. And Bachmann never backed down.

In politics and in her personal life, Michele Bachmann is defined by a striking certitude. Throughout her long-shot bid for the Republican presidential nomination, the 55-year-old congresswoman has portrayed herself as a leader who doesn’t waffle. Who upholds bedrock beliefs. Who tells it like it is.

Steady, planted, as constant as Iowa corn. “The consistent conservative,” the fervent born-again Christian says on the stump.

In the world she would create, the health-care reform law would be scrapped, the tax code would be rewritten, abortion and same-sex marriage would not be allowed, and schools could teach intelligent design along with evolution. God would be a more welcome presence in public life. “Today you’re not allowed to say ‘Merry Christmas’ at the post office,” she complains.

Bachmann’s admirers think of her as the real deal, a tea party favorite who does not dress up her conservatism with layers of ambiguity and political correctness. In a recent debate, as candidates were asked about interrogation tactics in the fight against terrorism, Bachmann was unapologetic in her support of waterboarding. “I think it was very effective and gained information for our country,” she said.

Debbie Smith, an Iowa businesswoman who supported Barack Obama in 2008, recalled the Bachmann moment vividly.“I love that she just put it out there,” she said “Even if I don’t always agree with her, I know where she stands. I’m tired of candidates who don’t say anything.”

Bachmann’s blunt talk is tempered one on one by a personal warmth, a likability. As she greets people, there is a flicker of the Miss Congeniality she once was — a mix of ingratiating attentiveness, sparkly brooches, fresh manicures. She does not stop smiling.

But the sureness that is Bachmann’s appeal also has been her undoing in the unforgiving glare of a presidential race.

She has a tendency to get things wrong, slipping up on facts, straining credibility with overstatements, taking shots that go too far. She prefers passion to policy fine points.

One recent evening with supporters in Des Moines, she assailed Washington’s culture of political favors by declaring: “I’ve had dollar bills waved in front of my nose, trying to buy me off. I never caved.”

Her exaggerations and gaffes go back to her earliest days in politics, said Lawrence Jacobs, a political scientist at the University of Minnesota who has tracked her since she started out.

“She has an affinity for land mines,” said Jacobs, who nonetheless said he admires her strategic instincts and the way she made it into the presidential field with limited financial resources and no support from the party establishment.

“People are wrong to discount her as a fringe candidate,” he said. “She did not get where she is by being irrelevant.”

In Waterloo, Iowa, Bachmann had a classic childhood of early-1960s America, a life of Wonder bread sandwiches and stay-at-home moms and weekend drives to see relatives. She walked home from school to eat lunch. She played outside until dark. She attended Lutheran church.

It was a stable, predictable world until she was 12, and the family moved to Minnesota so her father could take an engineering job.

She was crushed.

Then two years later, her parents split up, and “everything in our happy home changed,” she wrote in her newly published memoir, “Core of Conviction.” “. . .Security was gone. Stability was gone. And our dad was gone."

Her father left the house and then the state, remarrying in California five days after his divorce was final. Bachmann did not see her father again for six years.

In his absence, her mother reeled.

She worked as a store clerk and then a bank teller, earning $4,800 a year. She sold the house, the wedding gifts, even the china. All of it was placed “on little card tables out in the garage,” Bachmann recounted at a forum in Iowa, “and we just watched everything sold and sent away.”

The family moved into a cramped apartment, and the teenage Michele tried to make the best of her world’s collapse.

She took part-time jobs to buy her own clothes and lunches, while at the same time signing up for every activity she could at Anoka High School — 17 in all. She had a part in five school plays. Made the cheerleading squad. Earned good grades.

Twice she was named to the homecoming court.

But with no father there to walk her across the football field on homecoming day, the school principal had to step in, she recalled.

She vowed that her life would be different than those of her parents. That she would marry “a man who would be committed to me and to our family.”

She was by then a practicing Christian — not just a churchgoer, but a believer who attended summer Bible school and went to a prayer group before classes.

Still, some of her friends doubted that she had been saved. They asked about her relationship with Jesus. They prayed for her. She waved them off, she said, believing that she was a faithful Lutheran. But deep down, there was a “gnawing insecurity.”

Then, on Halloween night of 1972, Bachmann went with a small group to a church, thinking there was a party. Instead, she found herself in the sanctuary professing her faith as never before.

She returned home that night and knelt at the foot of her bed to pray. By morning, “I knew that I belonged to God,” she wrote in her memoir, “and that He loved me, and so I no longer had to depend on the approval of others.”

“Now I felt real confidence,” she wrote. “Profound confidence. Finally I felt armored and equipped, ready to confront the world and its many challenges.”

If faith was her first embrace, politics soon followed. At Winona State University, classmate Jerome Christenson said he drafted Bachmann as a candidate for his student government slate in 1977, thinking she would carry the Christian vote.

The slate won easily.

Back then, she and her future husband, Marcus Bachmann, considered themselves Democrats, as their families had been, and volunteered for Jimmy Carter’s 1976 presidential campaign. Both shared Carter’s born-again beliefs — and even went to see his inauguration — but grew disillusioned with his presidency.

One day, Bachmann was on a train, reading “Burr,” by Gore Vidal. It was a work of historical fiction, but she was offended by its tone, which she found mocking toward the nation’s founding fathers.

“I just thought, ‘This is a lie about the founders,’ ” she recalled in an interview. “. . . I put the book down and I looked out the window and that’s when I said to myself, ‘I don’t think I am a Democrat anymore. I really think I am a Republican.’ ”

It was not so much that Bachmann had a conversion that day, she explained, as it was that she clarified where she fit into politics. And over time, how politics fit into her faith.

Her marching orders came from God, and she didn’t doubt them. She and Marcus married in 1978 after they both had visions from God. She enrolled in law school — at Oral Roberts University — she once said, at God’s specific direction.

At the time, Bachmann’s life was dominated by her family, not by political ambitions. Although she worked as a lawyer for the Internal Revenue Service for five years, she gave up her job to concentrate on raising her children.

She and Marcus, a therapist who runs a Christian counseling center, also became foster parents to a long string of teenage girls, many of them being treated for eating disorders at the University of Minnesota and needing a place to live. As the girls attended public school, Bachmann grew dismayed by the lack of rigor in their schoolwork. She co-founded a charter school, lobbied to change education policies and then, in 1999, ran an unsuccessful campaign for the Stillwater school board.

“It was a chastening experience,” she wrote in her book. “Losing an election among your friends and neighbors is no fun. As a result, I resolved not to risk embarrassing myself ever again.”

Six months later, Bachmann took on a Minnesota state senator who had served for 28 years for the GOP endorsement.

She won.

Listening to a Christian radio station in November 2003, Bachmann heard about a court ruling in Massachusetts that would allow same-sex marriage and immediately wondered: Could Minnesota be next?

She had been a state senator for less than three years, a conservative Republican in a chamber controlled by Democrats.

“I took a walk and I just went to prayer — and I said, ‘Lord, what would you have me do in the Minnesota state Senate?’ ” she recounted in Iowa earlier this year. “And just through prayer, I knew that I was to introduce the marriage amendment.”

Over the years, Bachmann became a polarizing figure in Minnesota politics. She not only felt comfortable with conflict, she sought it out.

“If you were a conservative, you loved her,” said Warren Limmer, a GOP state senator and close ally of Bachmann’s in Minnesota. “If you were a liberal, you hated her. She’s really a comrade in arms; she will assault the beach. There is no middle ground if she is wed to the cause.”

After winning a seat in Congress in 2006, Bachmann became a prolific practitioner of dissent in Washington. She slammed Democrats, bucked GOP leaders, sounded alarms — and founded the House Tea Party Caucus in 2010.

“She learned very early on to go out there and say what she thought,” said Ed Goeas, a Republican pollster who worked for a time on her presidential campaign. “And it got covered, and she made news.”

Her fiery rhetoric and telegenic good looks have made her a Fox News Channel favorite.

When she caused a furor by questioning the patriotism of President Obama and Democrats in Congress — “Are they pro-America or anti-America?” — Sean Hannity and Rush Limbaugh leaped to defend her.

She did not apologize, saying: “I may not always get my words right, but I know that my heart is right.”

The kind of constitutional amendment Bachmann envisioned to ban same-sex marriage is on the state ballot in Minnesota for 2012. She feels certain the measure will pass, and proud that she contributed.

She and Helen LaFave still have not talked about the issue, which remains a source of some division within their family, LaFave and another relative said.

Asked about her stepsister, Bachmann said, “I absolutely love her. . . . She’s wonderful — and we disagree on this issue. We see it differently. You know you can have marriages where people disagree on basic issues, and you can have that with family members as well. And I do in my family.”

As a presidential candidate, Bachmann was the first to sign a pledge to support traditional marriage. She has held firm, she said, “because I knew it was right. I knew it was the right thing to do.”

Research editors Lucy Shackelford and Alice Crites contributed to this report.