Michelle Obama, after years of overt wariness toward politics, is shedding her reluctant image in favor of something unprecedented for a modern first lady: her own branded campaign.

Four years after an unsteady debut on the national stage, she is becoming the face of the campaign’s initiative to organize grass-roots supporters, holding events in cities across the country as part of the new “It Takes One” program. She is also talking increasingly about substantive policy, moving well beyond her trademark issues of childhood obesity and military families.

For a spouse who once expressed an aversion to politics and regularly said it took “convincing on Barack’s part” to get her on board, the approach represents a notable shift.

The first lady is “someone who never asked to be on the public stage and never aspired to be on the public stage but now has found a comfortable place,” David Axelrod, a senior adviser to the Obama campaign, said in a recent interview.

Perhaps. Or perhaps Michelle Obama is as attuned to the polling data as the rest of her husband’s reelection team — and has decided that, in an election that has been virtually deadlocked for months, every ounce of her enthusiasm could count. She said as much in an interview on the “Steve Harvey Morning Show” last week.

“We can’t assume we love Barack [so] he is going to be fine. No. That’s not how this works,” she said. “We have to be vigilant.”

That sense of urgency was not always a hallmark of the first lady’s rhetoric, which has undergone a dramatic evolution since her introduction to the electorate. While she was always an energetic backer of her husband’s, Michelle Obama peppered her public appearances with doses of doubt about the process, not to mention ample lighthearted criticism of her husband’s foibles (remember her complaints about his dirty socks?). She suffered for her flashes of honesty, most famously in 2008, when her confession that she had only recently become proud of her country brought a torrent of accusations that she was unpatriotic. She quickly revamped her image, clamping down on her spontaneity and, after moving into the White House in 2009, declaring herself “mom in chief” with little potential for controversy.

Her popularity soared, all the more so after she planted the first White House garden since Eleanor Roosevelt. But now, with the election just 31 / 2 months away and the polling consistently tight, she has loosened up — at least somewhat.

“At this point, what have you got to lose? This is your last national campaign. It really sort of frees you up for all kinds of strategies to win,” said Anita McBride, who served as chief of staff to former first lady Laura Bush. McBride recalled Michelle Obama’s performance in the 2008 campaign as “a little rocky,” saying she now appears to have a “completely different attitude toward the whole process.”

“Maybe this is what she understood campaigning to be at the very beginning,” McBride said, referring to the first lady’s grass-roots focus.

A campaign aide to the first lady said the “It Takes One” program was the first lady’s idea, originating with her first experiences of campaigning. She was there with her husband as he ran for state Senate, knocking on doors and sitting in living rooms talking about issues with “real people.”

“This has always been to her the most important thing,” the aide said.

While campaigning in Dayton on Tuesday, the first lady stopped by a phone bank to call supporters. Earlier in the day, she met with 10 volunteers in Columbus and asked them to lead Obama 2012 teams in their neighborhoods.

“She asked us to do more,” said Terri Arredondo, a campaign volunteer who signed up to be a team leader after chatting with the first lady. “She wanted each of us to take on more of a leadership role.”

Michelle Obama is also speaking more frankly about the policies most important to her. Before a large crowd of supporters gathered in a cavernous room at the Dayton Convention Center, she rolled out a new version of her campaign speech, including some lines that could have been delivered by the candidate himself.

“We believe that in this country, everyone should do their fair share, and that means teachers and firefighters shouldn’t pay higher taxes than millionaires and billionaires,” she said to applause.

Later she added: “This is also about the health of our families. . . . Because of health care, insurance companies have to cover basic preventative care — yes, things like contraception, cancer screenings and prenatal care, at no extra cost.”

Last month, at rallies in Nevada and Colorado, where the Obama campaign needs to win over Hispanic voters, the first lady was greeted by sizable crowds that roared their support as she spoke about immigration policy. Among her topics: her husband’s support for Dream Act legislation that would change the law to allow children brought to this country illegally to become citizens, and the action he recently took to stop deporting many of those young people.

“While this is an important step, it is not a permanent solution. So Barack is going to keep fighting to get Congress to give these young people a real pathway to citizenship. That’s what we’re working for,” she said.

In a more low-key way, Michelle Obama appealed to the campaign’s gay supporters this summer with a video response to questions she has received on Twitter. The video was not widely covered, but several LGBT Web sites picked it up and cheered the first lady for saying, “For Barack and me, it really comes down to the values of fairness and equality we want to pass down to our girls. . . . And in a country where we teach our children that everyone is equal under the law, discriminating against same-sex couples just isn’t right.”

The policy prescriptions Michelle Obama has begun to discuss are popular with the Democratic base, as is she. Nine out of 10 Democrats have favorable views of her, and at Obama campaign headquarters, staff members refer to the first lady as “the closer” for her appeal to volunteers to make one more call, register one more voter.

“She can help solidify and energize the base — African Americans, Democrats, liberals, unmarried women,” said Celinda Lake, a Democratic pollster. “She also helps with independent women. She validates voters positive feelings about Obama’s character.”

Michelle Obama has also navigated tricky terrain on behalf of the administration, signaling the role she could play if her husband has a second term. A few weeks after the president voiced his support for same-sex marriage, the first lady was the keynote speaker at the African Methodist Episcopal Church conference in Nashville, where nearly 30,000 leaders of black churches — many not supportive of gay marriage rights — were gathered.

Despite the opposition to that policy in the crowd, she brought listeners to a roaring ovation that ended in the gospel hymn “Victory Shall Be Mine” at the close of her nearly half-hour speech.

It was a speech that she largely crafted herself, laying out themes she wanted to address and editing it through meetings and e-mails with her East Wing staff, said Jocelyn Frye, the first lady’s director of policy. “She talked a lot about what she wanted to communicate and the different issues she wanted to raise,” Frye said. “This was very much her perspective.”

In those remarks, Michelle Obama talked about education policy, black history, civic engagement and the health-care law — in addition to childhood obesity.

“Much like they did 50 years ago, or 150 years ago, our laws still shape so many aspects of our lives: whether folks are paying their fair [share of] taxes or not; whether we invest in roads and schools, and the jobs that come with them or not,” she said. “You see, those decisions are made by the folks sitting in Congress and in our White House. They’re made by the folks in our state legislatures and city halls. And we all know who’s supposed to select those folks, don’t we? We know who’s supposed to tell those folks what to do, right? We are. That’s our job.”