DETROIT — Dana Nessel, who may be Michigan’s next attorney general, knows why she decided to become a lawyer: “I was obsessed with To Kill a Mockingbird,” the famous novel about a small Southern town and a country lawyer who values doing the right thing above all.

“All I wanted was to be Atticus Finch when I grew up,” she laughed. She has indeed has fulfilled that dream in many ways — but in one important sense, may have done even better: She wins.

Read last week’s column by Jack Lessenberry

In the novel, Atticus mounts a courageous and eloquent defense of a black man unjustly accused of attacking a white woman. But he loses in court, and his client is later killed by a mob.

Dana Nessel also has a track record of taking on impossible causes — and unlike Atticus, winning. Friends rolled their eyes when she agreed in 2012 to defend two gay nurses who wanted to jointly adopt three special needs children they were caring for.

The state was happy to place the kids in foster care with April DeBoer and Jayne Rowse, the nurses, but refused to allow both to jointly adopt them. Ms. Nessel challenged that, and only did she badly beat Michigan Attorney General Bill Schuette in federal court, the judge suggested she expand the case to include same-sex marriage.

She won on those grounds too, and her case was one of several that led to the U.S. Supreme Court decision recognizing that same-sex couples have a right to marry.

Then two weeks ago, she pulled off the biggest upset of all, winning what amounts to the Democratic Party’s nomination for Michigan attorney general in the November election.

Patrick Miles, the former U.S. district attorney for the western half of Michigan, was supposed to be the nominee. He is an African-American, and for years, Democrats feel they need to run a black candidate for statewide office — although they have sometimes given those nominees only token financial and political support.

Mr. Miles had the support of Barbara McQuade, the popular former federal prosecutor based in Detroit, and of U.S. Rep. Dan Kildee, the influential congressman from Flint.

More importantly, he was backed by both the AFL-CIO and the United Auto Workers union, historically decisive factors in Democratic Party politics. “The UAW does not lose,” said Bill Ballenger, a longtime observer of the state political scene.

But this time, the UAW lost … badly.

Party officials did not release final numbers, but when the thousands of delegates to the endorsement convention in Detroit’s Cobo Center voted, the 49-year-old Ms. Nessel won by a landslide.

She did have the endorsement of the main teachers’ union, the Michigan Education Association. But her victory was clearly mostly due to grassroots activists who showed up at was, for many, their first state party convention ever. Four years ago, barely 2,000 Democrats showed up for that year’s endorsement convention.

This year, more than three times as many did, some venturing from the Upper Peninsula during a freak mid-April snowstorm that dumped 20 inches on some communities.

“I think they appreciated that I visited so many of those counties,” Ms. Nessel said in an interview afterwards.

Indeed, she campaigned in 69 of Michigan’s 83 counties, with one simple and clear message: “I want to fight for you. I want to be the first attorney general since Frank Kelley to fight for consumer protection, to protect seniors and for the environment.”

“If that makes me a one-term attorney general, that’s fine, but I am going to do the right thing, and I’m not running for governor.”

Michigan has had three attorneys general since Frank Kelley retired in 1999 after a national record 37 years in the job.

His successors, Jennifer Granholm, Mike Cox and Mr. Schuette all used the office as a springboard for gubernatorial campaigns.

“I want to use it as a springboard to protect people,” she said. There is, however, something else different about her campaign.

When she won the endorsement, on the stage with her were her twin 15-year-old sons, Alex and Zach — as well as her wife, Alanna Maguire, whom she married soon after the Supreme Court decision.

Some worry this may be a political problem among older voters who still don’t accept same-sex relationships. The candidate doesn’t think so. “If I can enforce environmental standards, who can tell people I’m making sure their drinking water is safe, I don’t think they will care if I am a Republican or Democrat, straight or gay.”

When told that conservative columnist Nolan Finley charged that Ms. Nessel was “openly hostile towards men,” Bob Baldori, a Lansing-based attorney and accomplished jazz pianist burst into laughter. “She loves men. Is he kidding? Is he nuts?”

“I’ve been in crowds where she’s surrounded by big black men who adore her. Trying to define her by her sexual preference instead of the issues is ridiculous.” Ms. Nessel makes a face when told of the column; shrugs. She’s used to having her record distorted.

She’s also seen things that most people can’t imagine. For years she was an assistant Wayne County prosecutor, putting away child molesters and pornographers; car thieves, crooked cops.

Then, after being told she couldn’t do it, she went out and won case after case. Now, she is all but certain to be the attorney general nominee. Nobody can predict the course of any campaign.

It may not be clear till August who her Republican opponent is, though Speaker of the House Tom Leonard is the most likely choice.

But “I’m in it to win it,” Ms. Nessel said flatly.

She doesn’t seem to know any other way.

Jack Lessenberry is the head of the journalism faculty at Wayne State University in Detroit and a former national editor of The Blade.

First Published April 27, 2018, 12:00 p.m.