This is one in a seven-part series featuring the major GOP presidential candidates.

WASHINGTON — Michele Bachmann was an “accidental politician,” and it all began on April Fool’s Day.

On April 1, 2000, the 2012 Republican White House hopeful — then a “middle American mom,” as she wrote in her recent memoir — made a fateful, spur-of-the moment decision that changed her life.

She decided not to attend a wedding with her family and instead joined fellow Minnesota activists at a local Republican Party nominating convention. They wanted to put up someone to challenge their state senator, a veteran Republican lawmaker who they thought was turning soft and needed the fear of God put into him.

Bachmann became the sacrificial lamb. To everyone’s amazement, she knocked him off and went on to win the seat.

That was her first political lesson, Bachmann, now a three-term congresswoman from suburban Minneapolis, said in her book, “Core of Conviction.”

“With the right kind of popular energy, ordinary people can make a difference,” she wrote. “You can fight city hall … you can take on the establishment and win.”

Now her presidential hopes appear similarly challenging: She’s fallen from the top of the Republican field over the summer to the second tier as voting looms next month.

The 55-year-old political dynamo boasts of her “titanium spine.” She’s rarely demurred from taking on the establishment, even her own party when she’s deemed it not confrontational enough or committed enough to core conservative dogma.

When the House GOP leadership backed the debt-ceiling deal with the White House last summer and pressured its caucus to fall in line, Bachmann was a no-show.

Named Miss Congeniality in high school, Bachmann lobs political grenades like a commando in pearls. She recently called some of the other Republicans in the presidential race “milquetoast opponents.” She doesn’t blink an eye when she says she’d deport all of the estimated 11 million illegal immigrants in the country — “in steps.”

Like Ben Franklin with his kite, Bachmann lofts a line into the ether and quickly draws electricity. Appearing on MSNBC’s “Hardball” in 2008, she said that President Barack Obama “may have anti-American views,” then suggested that the news media should investigate the views of members of Congress “and find out, are they pro-America or anti-America?”

Sometimes her aim goes awry, as when she said that if she were in the White House, “we wouldn’t have an American Embassy in Iran.” There is no U.S. Embassy in Iran; it’s been closed since the 1979 hostage crisis.

Her religious faith has been her guide, she says. It’s why she became a lawyer, entered politics and chose her crusades.

Bachmann’s campaign didn’t respond to requests for an interview.

She grew up in Waterloo, Iowa. On the campaign trail, it’s her symbol of heartland values and a political touchstone.

“I believe we need a lot more Waterloo rather than Washington in the White House,” she said at a book signing last month in her hometown.

Her parents, both Democrats, divorced after moving the family to Minnesota. Earlier this year Bachmann told The Weekly Standard, a conservative political magazine, that she’d learned about poverty firsthand when her mother supported four children on her $4,800 annual salary as a bank teller.

Bachmann and her family reside in Stillwater, Minn. She and her husband, Marcus Bachmann, have raised five children and served as foster parents to 23 others. Marcus Bachmann is a therapist who runs a Christian counseling center whose methods are rooted in faith.

They were college sweethearts and Democrats who volunteered for Jimmy Carter’s 1976 presidential campaign. But they soon soured on the party of Truman and Kennedy and became religious conservatives. Her opposition to abortion and same-sex marriage has helped to define her political voice.

In Congress, she opposed the financial bailouts in 2008 and the Dodd-Frank law to regulate Wall Street and protect consumers. She’s also tried to eliminate provisions of the 2010 health care law.

Perhaps her most well-known piece of legislation, though, is the Light Bulb Freedom of Choice Act, which would repeal a 2007 mandate to phase out the less energy-efficient incandescent bulb. The bill hasn’t advanced past the House Energy and Commerce Committee.

Bachmann founded the House Tea Party Caucus last year, but she was unable to parlay that perch into a position in the House of Representatives leadership when the GOP took over last January.

The former federal tax attorney won the Iowa straw poll in August, the first test of candidate strength in the first state that will cast ballots in 2012, on Jan. 3.

But gaining the lead in the crowded field has been like quicksilver for most of the contenders. Except for former Massachusetts Gov. Mitt Romney, a fixture among the leaders, Bachmann, Texas Gov. Rick Perry and former Godfather’s Pizza CEO Herman Cain each seized the momentum at one point, then quickly lost it. (Cain has since quit the race.)

In Iowa, Rep. Ron Paul of Texas remains strong and former Speaker of the House Newt Gingrich is surging. The most recent Des Moines Register poll showed his support in Iowa among likely caucus-goers at 25 percent.

For Bachmann, the bad news is that the 22 percent support she attracted back in June has slipped to just 8 percent. The good news is that’s where she was in October, as well, so she appears to have halted her slide.

“No candidate has so far gotten even one-third of electoral support in any poll,” said Mark Meckler, a co-founder of Tea Party Patriots, a large tea party group. “To me, that shows it’s anybody’s to win.”

Bachmann has gone after Gingrich, accusing him of offering amnesty to illegal immigrants and being an “influence peddler” because of his private Washington consulting work.

Gingrich, in turn, has called Bachmann “factually challenged,” given her record of occasional gaffes. She once said that an Obama trip to India would cost taxpayers $200 million a day, a figure the White House called “wildly inflated,” and that the pivotal American Revolutionary War battles of Lexington and Concord — both in Massachusetts — were in New Hampshire.

It’s worth noting that at this point in the Republican presidential primary campaign four years ago, former New York Mayor Rudy Giuliani was leading the field. His closest rival, former Arkansas Gov. Mike Huckabee, was 11 points back.

Huckabee ended up winning Iowa, but he later dropped out. Giuliani was gone a few weeks later, while Sen. John McCain, the eventual GOP nominee, placed fourth in Iowa.

In a recent appearance on “The O’Reilly Factor” on Fox News, Bachmann said she was the “true, consistent conservative” and hopeful that voters would come around.

About 35 of them recently attended a meeting of Iowa’s Jasper County Republican Party. Chairman Dale Springer asked how many were “100 percent” sure whom they’d vote for on Jan. 3. Only about 20-25 percent raised their hands.

“That’s how up in the air this whole thing is,” he said.