Near the end of a post-election gathering in the heart of Marietta, Georgia tea party leader J.D. Van Brink asked whether the three dozen people assembled to talk about Donald Trump’s stunning victory missed the other big upset: Cobb County turned blue.

“No way,” two voices belted in unison. “It must be voter fraud,” another quipped. As the din quieted, one activist voiced the concern that jittery Cobb Republicans — and jubilant county Democrats — in this GOP stronghold have been asking themselves since last week’s stunning election.

“Is this the result of changing demographics? Or is this just an anomaly?”

Trump won a 5-point victory over Democrat Hillary Clinton in Georgia last week by running up huge margins in rural and exurban Georgia. But he lost every core metro Atlanta county to Clinton, giving Democrats a silver lining in an otherwise rough night.

The rising minority populations in Gwinnett and Henry counties made them ripe targets for a Democratic takeover. But even the most optimistic Democrat didn’t expect Cobb County, long the crimson-red lifeblood of the Georgia Republican Party, to flip this cycle.

Cobb hadn’t voted for a Democrat in a presidential race since Georgia’s own Jimmy Carter swept the county in 1976 — and even he was defeated in Cobb four years later. It was the launching pad for the political careers of Newt Gingrich, Sam Olens and Johnny Isakson. And it’s long been one of the most reliable sources in Georgia for GOP cash, votes and volunteers.

“I didn’t see it coming at all,” said Kennesaw Councilwoman Yvette Daniel, who considers herself the only Democrat on the Cobb city’s nonpartisan council. “But what this shows is people in Cobb County are tired of being left behind.”

Jerry Kotyuk, a Marietta tea party activist, put it a different way: “The demographics are changing. We are getting a lot more diverse. But nobody expected this.”

A Cobb collapse?

In a parallel universe, Clinton’s campaign would be celebrating Cobb as a blueprint for her victory. She hoped to defeat Trump by relying on an emerging coalition of younger and diverse voters, coupled with suburban college-educated conservatives skeptical of Trump.

That’s exactly the mix that helped her flip the county, where she outpolled Trump by about 6,800 votes — enough for a 2-point win. Republican Mitt Romney won the same county by 12 points in 2012.

Cobb GOP Chairwoman Rose Wing and other local party leaders cast it as a one-off, driven by Trump’s high unfavorable ratings, crude comments about women and a history of tepid support in the county, where his anti-establishment campaign didn’t play as well in a bastion of the state’s GOP establishment.

After all, Florida U.S. Sen. Marco Rubio won Cobb in Georgia’s March GOP presidential primary, and Trump’s campaign seemed to acknowledge its problems in the county when it dispatched Ivanka Trump to a pair of Cobb events weeks before the vote.

“As our Republican leaders implement common-sense, conservative solutions to get our nation back on track, we look forward to running on that record in four years,” said Cobb GOP Vice Chairman Justin Tomczak, who pointed to down-ticket wins in the county.

Indeed, Isakson earned nearly 53 percent of the vote in Cobb in his race against Democrat Jim Barksdale. Cobb Republicans swept every countywide office, running unopposed in most contests. And each of the GOP legislators held his or her ground. But their margins of victory point to longer-term problems.

Republican state Sen. Hunter Hill held on to his seat despite getting shellacked in the Cobb part of his district. State Rep. Rich Golick's 19-point win over a Democrat two years ago melted to a 6-point win over the same opponent this year. And state Rep. Sam Teasley's margin of victory shrank from 25 points to 14 in the past two years.

“We need to be reaching out not only to the people who traditionally agree with us, but also those not inclined to support Republicans,” said Teasley of Marietta. “I don’t think Republicans have to compromise what they believe in to show we are concerned with the issues that they are concerned about.”

The shifting demographics are more cause for concern for Cobb Republicans. In 2000, nearly three in four of Cobb’s residents were white. That number shrank to 64 percent in 2015. More than one-quarter of the county’s residents are black, and about 13 percent of the population is Hispanic.

A Democratic Cobb would change the political landscape in Georgia. The county is the fourth-most-populous in Georgia and one of the most affluent. If Republicans lose their grasp of Cobb, it could hobble the party in statewide elections in 2018 and the next presidential vote in 2020.

“If we lose Cobb, it becomes much harder for Republicans to win statewide,” said Jason Shepherd, a longtime GOP operative who worked for Gingrich. “You look down the road two years from now, and for the first time in years, Republicans are on the defensive in places like Cobb. And it’s going to be harder in midterm elections to keep up the momentum.”

Shepherd ran for county Republican chairman in 2015 and is considering another bid. He said last week’s results exposed the local GOP chapter’s “bunker mentality” that’s averse to newcomers and too willing to rest on its laurels.

Friendly fire

Confidence was on display at a Cobb GOP breakfast three days before the election, where activists talked matter-of-factly about mobilizing for the vote. Residents stocked up on signs for Isakson and U.S. Rep. Barry Loudermilk, who handily won a second term, but there was little mention of Trump.

“Republicans can agree to disagree,” Wing told the few dozen attendees, referring to skepticism of the GOP nominee. “As Ronald Reagan says, 80 percent of my friend doesn’t make you my enemy.”

The hand-wringing began hours after the election. Sheriff Neil Warren, whose margin of victory also narrowed from 2012, said he was “very sad and disappointed” that Trump lost Cobb. Others cast the blame on Wing and activists who supported Texas U.S. Sen. Ted Cruz in Georgia’s presidential primary.

Democrats, meanwhile, hope to ensure the victory is not fleeting. Coakley Pendergrass, a 72-year-old former New York police officer, devotes an increasing chunk of his time trying to recruit candidates for low-level offices, from city council races to state legislative contests.

“I truly believe that Cobb County is on the verge of flipping down the ticket, and we’re working on it now. It’s about putting people in the right place,” Pendergrass said. “Look at it as a sports analogy: You’re playing tennis and you take what your opponent gives you. This is what they gave us this cycle.”

Republicans promise to come roaring back. Tomczak said the party is looking for new ways to expand in the era of Trump. And Van Brink, the tea party leader, said he’s confident the pendulum will swing the GOP’s way again by doubling down on its conservative principles.

“I have more in common with a black female entrepreneur than a white male socialist,” said Van Brink, who is white. “We don’t believe that demographics is destiny. And if we can translate our conservative values and principles to public policies, we’ll be fine.”