In Michigan, Harris works to solidify union support amid signs some of it could be slipping to Trump

Visitng a firehouse in Redford Charter Township, outside Detroit, the vice president shouted out to "labor brothers and sisters" that the tentative dockworker agreement demonstrated the power of collective bargaining.

"We know, when union wages go up, all wages go up," Harris told a small firehouse crowd featuring representatives from different unions. "And the bottom line is, when unions are strong America is strong."

She also directly went after her opponent, saying Trump "has been a union-buster his entire career" who would launch a "full on attack" against organized labor.

Trump is "making the same empty promises to the people of Michigan that he did before," Harris said, "Hoping you will forget how he let you down."

Harris was set to speak later in Flint and her campaign said she'd use those remarks to criticize Trump and his running mate, JD Vance, on auto jobs. She planned to point directly to Vance, who while campaigning in Michigan on Wednesday refused to commit to continue federal support going to the GM plant in Lansing.

Unions have long been a bedrock of support for Democrats, but Harris has failed to secure some key endorsements. The International Association of Fire Fighters announced this week that it wouldn't back a candidate this year, following a similar announcement from the Teamsters. Both unions endorsed Joe Biden four years ago.

Still, Harris was introduced and endorsed at the firehouse by Matthew Sahr, president of Michigan firefighters. Similarly, some Teamsters groups have publicly backed the vice president even as their national union has opted not to make formal endorsements.

There were nonetheless warning signs for Harris.

Justin Pomerville, the business manager at UA Local 85 in Michigan, said 70% of his members' work hours are tied to the CHIPS and Science Act, which the Biden administration championed and pumped billions of dollars into semiconductor manufacturing.

The workers lay complex networks of pipes that carry exhaust, water and chemicals through high-tech facilities. However, Pomerville said that some members aren't aware of the connection between their jobs and the legislation.

"Unless someone tells them they're working because of that, they don't know," he said.

It's not a total cold union shoulder for Harris. She won quick endorsements from national teachers unions, the building trades, the AFL-CIO and the United Auto Workers after replacing Biden at the top of the Democratic ticket.

But the divide within the labor community is a reminder of shifting loyalties in American politics. Democrats have increased their support among white-collar professionals while Republicans try to make inroads among voters who didn't attend college.

During a rally in Saginaw, Michigan on Thursday, Trump claimed that Republicans are now "the party of the American worker," glossing over his anti-union record as president. In a reference to labor unrest at the country's ports, he insisted that "under my leadership Americans won't have to go on strike for a better wage or a better life."

The former president also made a trip to Flint last month in an event billed as focusing on the auto industry, a pillar of the battleground state. The two candidates have been in the same cities — and in some cases the exact same venues — within days or weeks of each other.

Pomerville, who is also president of the Tri-County Building and Construction Trades Council, said "We're voting our pocketbooks" and "It's got to be our job to get that message out."

But he warned that "Trump has done an amazing job at marketing false facts" and his message is resonating with some of the union members.

"It's particularly potent with men who appreciate his anti-establishment message and are exhausted by politics in general," said Pomerville who added that when people try to talk about the election with them, "you can watch some of their walls go up."

Trump was spending Friday in Georgia with Gov. Brian Kemp, the latest sign that he's patched up his rocky relationship with the top Republican in a key battleground state. Later in the day, he's holding a campaign event in Fayetteville, North Carolina.

Union voters have traditionally leaned toward Democrats, with 56% supporting Biden in 2020. But Trump has pushed hard to win over blue-collar workers traditionally represented by some of the biggest unions. He won 62% of white voters without college degrees — though only 24% of non-white voters without college degrees — in 2020.

It's frustrating for Democrats, who point to the country's strong labor market — 254,000 jobs were added in September, more than expected — and the White House's firm support for unions. Biden even joined a UAW picket line last year.

Labor relations could have been a dominant issue in the closing weeks of the presidential campaign if the dockworkers strike continued, leading to snarled ports and shortages on store shelves.