Michelle Obama’s opening-night appearance at the Democratic National Convention is a reflection of her huge popularity with the Democratic base. (Jacquelyn Martin/AP)

Nine years ago, Michelle Obama was a reluctant political spouse. The Chicago hospital executive made little secret of her distaste for the process as she stepped onto the national stage, calling partisan politics a cynical business. Her raw authenticity, at times, hurt her husband’s campaign for the presidency.

Today, the first lady is a fully evolved political superstar, hugely beloved within the Democratic Party and a force within popular culture. Handed a prime-time speaking spot at the Democratic National Convention on Monday, she has been tapped to serve as a crucial validator for Hillary Clinton among groups who may remain skeptical of the party’s nominee.

“I’m glad that she was selected to speak on the first night, the opening night of an historic convention,” said Donna Brazile, the longtime Democratic strategist. “The country trusts her. People know she’s authentic and will be honest, and [they] want to know what she thinks.”

In nearly eight years as first lady, she has deliberately avoided partisan issues — but in her address she will fully endorse Clinton. According to an official familiar with her written speech, she plans to talk about the role a president plays in the lives of the nation’s children, shaping their values and aspirations. She will also discuss why she thinks Clinton has the “character, temperament and experience” to be president, and how Clinton’s career reflects ideals such as “opportunity, equality, inclusion.”

Personally, it’s a big step: Mrs. Obama hasn’t been particularly close to the Clintons in the years since her husband’s bruising 2008 primary campaign against Hillary Clinton. But now, the legacy of President Obama’s administration rides on her victory.

“She is there, in part, to be a coda and also to be a bridge,” said Andra Gillespie, a political scientist at Emory University who studies political mobilization. “She’s there to wrap up the Obama administration and provide a transition to what a Clinton presidency could be.”

Her opening-night slot reflects more than just her steady popularity: Organizers also appreciate her unerring knack for making headlines — and capturing the attention of people who don’t otherwise follow the news cycle closely. Come Tuesday, there will be stories about everything from how warmly she spoke about Clinton to which fashion designer’s clothing she wore.

Even while absent from the action, she ended up at the center of the news last week when Melania Trump’s speech at the Republican National Convention turned out to have borrowed from her 2008 DNC speech, and the Trump campaign was forced to acknowledge that Melania is an admirer of Michelle’s. (She stayed mum throughout Melania’s ordeal.)

Melania Trump’s speech at the GOP convention in Cleveland is drawing comparisons to Michelle Obama’s speech at the 2008 Democratic National Convention in Denver. Here’s a side-by-side look at both. (Jenny Starrs/The Washington Post)

It was an ironic flub for the Trumps — after all, the decision to have the first lady open the convention for Democrats is not without peril. For all her popularity among party faithful and young pop-culture obsessives (57 percent of Americans viewed her favorably in a January 2015 Fox News poll), she may not be the most effective figure for wooing swing voters or peeling off Trump-skeptical Republicans.

While her predecessor Laura Bush was viewed warmly by many Democrats even as their disdain for her husband grew, many Republicans see Michelle Obama more unfavorably. In a 2014 Pew survey, 46 percent of Republicans rated their views of her as “very unfavorable.”

Conservative pundits have portrayed her advocacy for healthy food and exercise as a scolding, big-government intrusion into private lives; other critics have turned up their noses at her easy fluency in youthful hip-hop culture. Wall Street Journal columnist Peggy Noonan described the first lady’s appearance at the 2013 Oscars as “disquieting” and questioned “this White House’s lack of hesitation to insert itself into any cultural event anywhere.”

As it happened, Michelle Obama’s most visible appearance last week was her instantly viral “Carpool Karaoke” segment with “The Late Late Show” host James Corden, in which she sang along to Beyoncé’s “Single Ladies” and rapped along to Missy Elliot’s 2001 hit “Get Ur Freak On,” accompanied by Elliot herself. Vanity Fair, upon seeing this, dubbed her the “Coolest First Lady.”

In her DNC remarks, though, she will attempt to connect her life story to broader political and policy themes. Her personal narrative of being reared in working-class Chicago shows up in nearly all of her speeches, and she probably will use it again to motivate the young people Democrats want to turn out to vote.

In February 2013, Michelle Obama made a surprise appearance on the Academy Awards show, via satellite, to present the best picture Oscar. (Pete Souza/The White House)

Her “Carpool Karaoke” segment on “The Late Late Show With James Corden” was just the latest of her many efforts to make a mark on popular culture. (CBS/via AP)

“The first lady takes a very active role in her speeches,” Tina Tchen, the first lady’s chief of staff, said in an interview earlier this summer. “She wants to communicate that ‘these are the circumstances under which I grew up, and I never dreamed I’d be in the White House, and now I am, and you can do that, too.’ That’s a theme woven through her speeches.”

Over nine years of telling and retelling her trajectory from the South Side to the Ivy League to motherhood and a legal career, her story has become more polished — thanks in part to the small cadre of White House speechwriters who have channeled her voice.

In 2007, she would try to connect with other women over their household duties, “doing a lot of juggling, a lot of balancing,” as she told a New Hampshire crowd: “For the most part, if a toilet overflows, we’re the one scrambling to change the meeting time to be there to meet the plumber. Can I get an ‘Amen,’ ladies?”

Stories like that have fallen away now that she is a globe-trotting first lady. She continues to describe her own family life as busy but affectionate. Yet it has been a long time since she sounded as if she was writing her own speeches.

Democrats have high expectations for what she will bring to this political moment, particularly after Clinton’s choice of mild-mannered Sen. Timothy M. Kaine of Virginia as her running mate, said Jamal Simmons, a Democratic strategist who served as DNC communications adviser during the Obama 2008 campaign.

Clinton is “going to need to create as much sex appeal around her candidacy as she can,” Simmons said. “People will be looking for some excitement.”

The big stage also provides an opportunity for Obama to foreshadow the role she hopes to play after January 2017. The first lady has spoken of the isolation she feels living in the Executive Mansion. While riding with Corden, she mentioned how rare it was for her to be riding in the front seat of a car, listening to music.

Clearly, she is ready to regain more control over her private life. But her speech may hint at her future as a public figure.