Support for President Donald Trump can be found on the picket line, but members of the United Auto Workers union are wondering whether the champion of Michigan’s blue-collar workers supports their strike against General Motors as demonstrations finish their third week.

Michigan’s autoworkers are at the center of an ongoing labor dispute that could have implications for Trump’s reelection prospects in Midwest battleground states. Trump touts his appeal among blue-collar autoworkers as one of the chief reasons he became the first Republican to win Michigan in nearly three decades but he’s avoided weighing in on the conflict, giving Democrats an opportunity to court a key part of his base.

“He wins the presidency and all sudden he’s nowhere to be found,” said Stephanie Carpenter, a 44-year-old employee at GM’s Romulus Propulsion Plant. “Everyone’s like, ‘where are you at?’ I don’t see him with American workers out on this picket line, showing his support.”

Nearly 50,000 UAW members joined the strikes three weeks ago, which continues as the union pushes GM to raise wages, reopen shuttered plants and increase pay for temporary workers. Every major Democratic candidate quickly sided with the labor union, while four Democratic primary candidates -- Bernie Sanders, Elizabeth Warren, Amy Klobuchar and Tim Ryan -- visited striking auto workers in Michigan.

The president told reporters on the first day of the strike he was “sad to see” the situation and celebrated his “great relationships" with the autoworkers. Trump never took sides in the conflict and hasn’t publicly said much else since.

“The UAW has been very good to me,” Trump said on Sept. 16. "The members have been very good, from the standpoint of voting. The relationship is good. Hopefully, they’re going to work that out quickly and solidly.”

Warren and Sanders, who both made standing against corporate greed a central part of their political brand, struck a sharper tone in support of striking workers in Michigan. Warren said GM is demonstrating a lack of “loyalty” by not sharing its prosperity with employees, while Sanders condemned GM for increasing production in Mexico and China as it idles American plants.

Meanwhile, strikers on the picket line outside GM’s Detroit-Hamtramck Assembly said Trump’s absence is noticeable.

“In lieu of everything that happened, he has not been here at all,” said Doris Parnell, a 67-year-old retired GM employee. “He’s always gone to (out-counties) where his star supporters are. He has not been out here, he has not publicly said ‘I support those workers out there.’"

But outside GM Technical Center in Warren, union workers said their support for Trump hasn’t wavered.

“I don’t see the Democrats have ever done anything of any use for any union,” said Lee McGuire, a 64-year-old GM employee. “You know I’ve been living through all of this for 40 years and all I’ve seen is our jobs eroding and eroding. I’d like to see my grandchildren have a shot of a decent living working for General Motors and Ford and Chrysler.”

Voters like McGuire in Macomb County, the state’s third-largest county, were instrumental in Trump’s 2016 victory.

Former President Barack Obama won Macomb County twice, but Trump reversed the GOP’s 4-point loss in 2012 to a commanding 12-point victory four years later. Trump won Michigan by just 10,704 votes but picked up 48,300-vote margin of victory in Macomb County.

“We back our union because we back each other, we don’t necessarily have to agree with our elected officials,” said Mike McKay, a 68-year-old GM millwright. “They have a certain persona they have to maintain. The rank and file, I don’t know anybody that is a staunch Democrat anymore like it used to be.”

The Michigan Democratic Party keyed in on announced plant closures in Michigan and the impact of steel and aluminum tariffs imposed by the Trump administration as evidence that he failed to uphold promises to auto workers.

The Detroit-Hamtramck Assembly is scheduled to close by the end of the year. Production at General Motors’ longstanding transmission plant in Warren stopped in July as part of GM’s plan to reduce operating costs.

Will Noronn, a 43-year-old GM employee, was transferred to the company’s Flint Assembly after it announced plans to idle the Detroit plant. Noronn said Trump failed to uphold his campaign promises by not intervening in plant closures in Michigan and Ohio.

The president told autoworkers at the Lordstown Assembly in Ohio not to sell their homes in 2017, saying factory jobs would return to the state. GM announced it will idle the facility in 2018 and the last day of production finished in March.

“We have a lot of those (Lordstown) employees now in Flint, some of them are making the (more than) 200-mile drive back and forth to see their family on the weekends because they can’t afford to move yet,” Noronn said. “It’s been tremendously disastrous because that plant, like Detroit and Flint has been instrumental within the community.”

Most of the largest labor unions, including NEA, the SEIU, AFSCME, UFCW and UAW, endorsed Democratic nominee Hillary Clinton in the 2016 election. Though labor union members were long considered a crucial voting bloc for Democrats, Michigan Republicans suggest Trump has a unique appeal among them.

“We have not seen the excitement from autoworkers for a candidate on any side of the political aisle like we did in 2016,” said Michigan Republican Party Co-Chair Terry Bowman, a Ford employee. “I have called (Trump) the blue-collar billionaire because he speaks the language of everyday Americans. He has the ability to look in the camera to be at a rally and to really focus and connect with the workers that are looking to him for leadership.”

Bowman said maintaining the support of autoworkers is paramount to Trump’s reelection hopes. He said Trump has nothing to worry about, but the Michigan Republican Party declined to comment on whether Trump’s reluctance to weigh in on the strikes is likely to help or hurt him in 2020.

U.S. Rep. Debbie Dingell, D-Dearborn, said Trump should stay above the fray while addressing the Detroit Economic Club. Dingell was president of the General Motors Foundation and was an executive director of community and government relations at the company.

“I think that this in many ways about the future of manufacturing in this country,” Dingell said. “When Henry Ford began manufacturing in this country, he said if you pay a decent wage and you have a strong middle class then there is money that is supporting our economy. I think politicizing a strike would be an immense mistake and come at a cost to (Trump).”

Trump had less union support than Clinton in 2016, according to Harvard’s Cooperative Congressional Election Study, but her margin of victory was smaller than former President Barack Obama’s in 2012. An estimated 38% of labor union members voted for Trump in 2016, but McGuire suspects the number is even higher.

“The UAW is constantly (telling you) 'vote Democrat, vote Democrat,” so to find someone who will admit they’re a Republican is a little difficult," McGuire said. “Honestly, I sit here and talk to the other guys and there’s not one of them talking about the Democratic policies.”

How to best extend health coverage to millions of uninsured or under-insured Americans is among one of the top policy debates defining the Democratic primary. Striking autoworkers told MLive they largely opposed Democrats’ “Medicare for All” plans, regardless of their political affiliation.

Sanders and Warren are championing a single-payer government-run approach that would extend Medicare to all Americans. The plans would eliminate the need for private insurance and employer-provided health care.

Matt Kalinowski, a 30-year employee at the GM Technical Center in Warren, worries the health care plan he fought for and sacrificed wage increases for would be replaced with inferior coverage.

Trump often tells voters he’s kept his promises to autoworkers -- renegotiating trade deals, spurring new investment in domestic factories and keeping manufacturing jobs in the U.S. -- regardless of his rocky relationship with union leaders and auto executives.

Several UAW members on the picket line said Trump can’t be pro-labor and anti-union at the same time. Dan Sultana, a 55-year-old Ford Motor Co. employee, said the president is merely exploiting autoworkers’ economic anxiety for his own gain.

“Any good union person that supports Donald Trump needs a good education right now,” Sultana said. “Donald Trump says what he needs to say when he needs to say it.”