The International Association of Fire Fighters has joined the International Brotherhood of Teamsters in declining to make a presidential endorsement this election season. Perhaps most worryingly for Harris, both cited feedback from rank-and-file members as the reason behind their decisions.

“Over the past year, the IAFF took unprecedented steps to hear our members’ views on the candidates and the policy issues that matter most to them,” the union’s general president, Edward Kelly, said in a prepared statement. “The IAFF Executive Board determined that we are better able to advocate for our members and make progress on the issues that matter to them if we, as a union, are standing shoulder-to-shoulder.”

“Standing shoulder to shoulder” apparently means not backing either candidate, though Kelly said the vote among the executive board was close. Both IAFF and the Teamsters had consistently endorsed Democratic candidates dating back to the 1990s, both endorsed President Joe Biden, and both represent a largely white male, non-college-educated workforce.

In IAFF’s case, the contrast between 2020 and 2024 is even more stark. It was the very first union to endorse Biden when he announced his candidacy, showcasing enthusiastic support for his bid. But it also declined to endorse Hillary Clinton in 2016, indicating a particular weakness she and Harris have with its membership.

“Harris’s lack of endorsement from the IAFF, following the Teamsters’s decision, suggests a broader growing issue for Democrats with union support, especially among non-college-educated white men,” Democratic strategist Tom Cochran said. “The fact that both Harris and Clinton failed to secure the IAFF’s backing while Biden did raises questions about whether this is more about the party’s broader struggles with blue-collar workers than the candidates themselves.”

But Cochran, a partner at 720 Strategies, doubted the problem was the candidates’ gender, adding, “The bigger issue seems to be a disconnect between Democrats and organized labor.”

Any slippage in union support will be a worrying factor for the Harris campaign through Election Day, even as she gains with broader demographic groups such as women and college-educated voters.

Biden and Harris are both strong backers of organized labor, and Harris has received the support of most major unions, but Biden brought decades of experience with the groups and loved to share stories of his “Scranton Joe” upbringing in working-class Pennsylvania. That’s a more difficult connection for Harris, a California native whose parents held doctorate degrees, to make.

Polling bears out that she struggles in particular with white men. A recent CNN poll found former President Donald Trump leading with that group, 58%-35%, while white women still favor Trump but by a much smaller margin of 50%-47%.

Teamsters internal polling found a huge drop-off from Biden to Harris. The union’s membership preferred Biden over Trump by 9 points, but after he quit the race they went for Trump by 25 points over Harris.

The issue for Harris isn’t just with white men, however. An NBC News-Telemundo-CNBC poll of Hispanic voters found Harris leading with the demographic overall by 9 points but trailing with working-class Latino men and with all Latino men under 50.

Dan Bowling, who teaches labor courses at Georgia State University’s law school, said he wasn’t surprised at the IAFF snub, and pointed to issues the union had with Democrats that predate the Biden-Harris switch. The union pushed back against COVID-19 vaccine mandates early in Biden’s term, for example.

“A firefighter, male or female, is a different breed of cat, and they fit right into the trend that we’ve been noticing of people with blue-collar jobs, whether they’re building factories, delivering goods, or fighting fires, relating far more to Trump,” Bowling said.

Bowling mentioned previous elections such as 2012, when the IAFF endorsed President Barack Obama over GOP challenger Mitt Romney, as evidence its members are not necessarily looking at demographics.

“Romney is not a guy with grease under his fingernails,” Bowling said, contrasting him with Trump’s image as a developer who has been photographed wearing a hard hat at construction sites.

The Trump campaign is aggressively courting union voters this cycle, calling itself the most pro-worker Republican ticket in history.

That’s not to say all IAFF members are on board for the GOP ticket.

In late August, vice presidential nominees Sen. J.D. Vance (R-OH) and Gov. Tim Walz (D-MN) each spoke at the IAFF’s convention in Boston. Vance was booed by some of the members and had to plead his case with them.

“Sounds like we’ve got some fans and some haters,” Vance responded as he appeared onstage. “That’s OK. Listen to what I have to say here, and I’ll make my pitch.”

Walz, in his appearance, told the group he’s proud to be a “card-carrying” member of his state teachers union and said Harris would help pass the PRO Act, which makes it easier for workers to organize.

Vance brought up larger issues, citing an inflation and affordability crisis that has strained budgets and pensions, in addition to an influx of illegal immigration and drugs he said have burdened first responders like firefighters and EMTs, as evidence of Democratic failures.

“I’m asking you to ignore the campaign rhetoric and look at the record,” he said. “In 2019, this union endorsed a Democrat for president with high hopes. But sadly, I believe you’ve been let down.”