In Atlanta's suburbs, is a political revolution brewing?

Amid honking horns and kids waving “Vote Your Ossoff” signs, Lisa Duncan relishes the excitement driving Jon Ossoff, a Democrat, to a commanding lead in a district that Republicans have owned since the 1970s.

“Jon is a really positive guy, and he’s part of a movement to get smart people in that are sincere, conscientious, and want to stay with the party,” says Ms. Duncan, a local activist. “So, not negative – that’s what we really need.”

As she talks, a lot of drivers honk, their thumbs up; a man in a pick-up truck boos, his thumb down.

Duncan is one of thousands of anxious Georgian Democrats in search of hope at the ballot box. She says she has found it in Mr. Ossoff, a 30-year-old documentary filmmaker whose name recognition has skyrocketed as the stakes have risen here in Atlanta's northern suburbs.

A big question for Ossoff and other Democrats vying for success in conservative corners of the United States is whether the anti-Trump sentiment that has reared up in rallies and town halls is deep enough to sway a race in a state that handily elected Trump in November. It’s a question that’s cropping up unexpectedly in Republican strongholds from Georgia to Kansas to Montana, where districts that the GOP has held for decades are suddenly developing a tinge of violet.

Such contests, like the one to represent Georgia’s Sixth District – Newt Gingrich's old district – are giving Democrats a chance to hone a new bargain with American voters, one that favors economic populism, social justice, and reclaims the mantle of the working class. Some pundits call them a new breed of Democrats. For Duncan, it’s an effort to “take [Democrats] back to their strength and their values.”

Democratic candidates “like Ossoff will try to capitalize, perhaps not intentionally, on the same attitudes that helped Trump. They’re outsiders who can tap into the same voters who are dissatisfied with what they see happening – [a] ‘curse on both your parties,’ ” says Chuck Bullock, a University of Georgia political scientist. “This is a time to take out incumbents where [rookie candidates] can say, ‘I haven’t been part of the problem.’ ”

What would in calmer days have likely been a sleepy special election important only to partisans has become a wide-open race with national attention. At rallies around the suburban district, the energy has been akin to a state fair, in no small part because voters concerned by the early days of the Trump presidency sense an upset-in-the-making.

“There’s a renewal of civic engagement in America right now,” Ossoff, a former congressional aide who comes off as earnest, yet polished, says in an interview. From the environment to reproductive rights to press freedoms, he says, “there’s a greater awareness of the stakes and the consequences of inaction than any time in recent history. That’s why folks here in Georgia are, as you can see, so intensely engaged in this campaign. The stakes are high.”

Aside from Ossoff, Democrats trying to breach red state bulwarks include Montana rancher and troubadour Rob Quist, whose campaign notes that “there’s nearly 300 millionaires in Congress but not one Montana folk singer,” and Kansas Democrat James Thompson, who has forced Republicans to play defense in the run-up to a special election Tuesday in what was once a safe district. His latest ad features him firing an AR-15 while a narrator calls him a “fighter who grew up in poverty.” Republicans are concerned enough that President Trump recorded a last-minute call this week urging people to vote for Republican Ron Estes.

A first-time win for Democrats?

Democrats haven't won the district since Mr. Gingrich won it in 1979, the longest such drought in the state. But Ossoff has a commanding lead in an 18-person field, including 11 Republicans, several of whom are battling to hoist Trump’s standard. And Ossoff has surged, breaking fundraising records and raising more than $8 million from nearly 200,000 individual donors, much of it pouring in from other parts of the country.

The Georgia Sixth District is “better educated, more sophisticated certainly than most Georgia districts and probably most districts around the country, so that assumes that a larger share of the electorate would be attentive,” says Professor Bullock. A higher turnout likely won’t be fueled by “real hard-core partisans,” he says, but by less politically active people “inspired to go to the polls.”

That’s enough to make Republican operatives like Todd Rehm, the editor of GaPundit.com, nervous. How nervous? “I’d say a 7.5” on the anxiety scale, he says.

The hints of a possible shift were there: Hillary Clinton won in Cobb County, which is part of the Sixth and only lost the district by 2 percent. And Tom Price, who left the district to become Trump's Health and Human Services Secretary, had seen his once decisive vote totals dwindling in recent elections.

Ossoff is shooting for a 50 percent + 1 vote knockout in the so-called "jungle primary" on April 18. He is currently polling at 42 percent. But if a Republican snags the second spot for June, Ossoff will face a more concentrated Republican machine.

Liberal Moms of Roswell

For his part, Ossoff agrees that, in some respects, he has become a vessel for a broader political movement.

He also acknowledges one group of voters in particular have fueled his campaign: women. "I think the most interesting part of the story is the thousands of people, mostly led by women, standing up to make a difference."

Count Emile Toufighian among them.

Two years ago, feeling lonely, Ms. Toufighian started Liberal Moms of Roswell and Cobb as a social club, expecting maybe 10 people to join. Turns out she wasn’t as lonely as she thought. Her group now has more than 1,700 members. She says it’s one of a growing number of “resistance groups” that are tipping from energized voter to full-fledged street activism. Up until now, she says, “I felt like I had no voice.”

“People are definitely shifting their focus,” says Toufighian, a Roswell, Ga., midwife. “There’s been a sense of looking to other people to get it done, then realizing, after the election, ‘Wait, this is us – we’ve got to produce these candidates or be these candidates.’ ”

'Can't solve actual problems if we're all extremists'

Among the outsiders is Debra Rodman, an anthropologist running for the Virginia General Assembly.

As part of what’s been called a “huge organic surge” of women candidates in Virginia, Professor Rodman, a professor at Randolph-Macon College in Ashland, Va., joins 42 other Democrats running to represent districts currently held by Republicans. In 2015, only 21 Democrats challenged incumbent Republicans.

Advisers have asked her to tone down references to her volunteer work with Syrian refugees, especially Muslim women, helping them to adjust to life in America.

Given Trump’s win in November, she says she is ignoring such advice, noting that “being moderate and centrist, I don’t think that’s worked, and I don’t think it’s going to work.”

To her, the electoral formula is a mix of “integrity” and holding true to “very progressive values” around immigration, women’s rights, and education but also bolstering the working-class economy.

“True Democratic values have to hold true to very progressive values,” says Rodman. “We can’t go too center because then we’re not speaking to the people who really need us – and we are us. I’m a college professor, but my husband [drives a forklift at a brewery], we struggle to pay the bills, we have a child with special needs, we struggle to get health care.”

“This is about helping neighbors. We’re all in the same struggle.”

She says the Georgia election and next month’s gubernatorial primaries in Virginia are testing a message that “is not quite formed yet, but that we’re seeing emerge.” The Virginia general election is in November.

At a rally on Tuesday in Dunwoody, Ga., baby boomer Paul Flexner says a lot of Americans like him are ready to see a younger generation step up to the plate, if only to get a fresh perspective. Ossoff's focus on shared values over partisan talking points also resonates with him.

"More and more people realize that the problem in this country is that we've lost the political middle," he says. "We can't solve actual problems if we're all extremists."

Correction: This article has been updated to clarify that, to win outright, a candidate in the Georgia Sixth District would need to win 50 percent of the vote, plus 1.