Richard Trumka, a third-generation coal miner who became one of the nation’s most politically influential labor leaders, representing more than 12 million workers as the president of the AFL-CIO, died Aug. 5 at 72.

His death was confirmed by labor federation spokesman Tim Schlittner, who did not provide additional details. Speaking to reporters Thursday, President Biden called Mr. Trumka a close friend and said he died while on a camping trip with family.

A powerful force in Democratic politics, Mr. Trumka sought to reinvigorate the labor movement after years of declining union membership, linking the campaigns for job security, better wages and improved working conditions to causes including the fight for racial justice. He cast himself as a spokesman for American labor as a whole, not just the more than 50 unions that make up the AFL-CIO, the nation’s largest labor federation.

“The labor movement is the best vehicle out there to make broad social change that creates an America where everyone gets a chance to win once in a while, not just the people on Wall Street but every American out there,” he told The Washington Post in 2009, shortly after he was elected the federation’s president.

A former head of the United Mine Workers of America, Mr. Trumka had a thick mustache, bulldog physique and confrontational manner — “more fire in the belly,” as labor historian Gary N. Chaison once put it, than many other recent union leaders. With his blue-collar upbringing and law-school education, he was comfortable both on Capitol Hill and in the mining country of Appalachia and the Midwest, lobbying for labor protections or rallying on the picket line.

As head of the AFL-CIO, he launched initiatives aimed at reaching younger workers, championed the “Fight for $15” effort to raise the minimum wage and called for employees to have a voice in ensuring their workplaces have proper safety protocols during the coronavirus pandemic. He recently championed the White House’s push to pass a bipartisan infrastructure bill, in addition to legislation that would strengthen labor laws.

For a time, Mr. Trumka found common ground with President Donald Trump in their shared opposition to trade deals such as the Trans-Pacific Partnership and North American Free Trade Agreement, which he blamed for a loss of manufacturing jobs. He played what Reuters described as “a make-or-break role” in securing Democratic votes for NAFTA’s successor, the revised U.S.-Mexico Canada Agreement, which Trump signed in January 2020 after the president agreed to changes on workers’ rights and other issues.

“President Trump may have opened this deal. But working people closed it,” he said in announcing the AFL-CIO’s endorsement of the deal. “And for that, we should be very proud.”

Mr. Trumka was initially known for his fiery leadership of the UMW, where he had started his career as a lawyer. He enlisted mine workers to support the anti-apartheid movement in South Africa, spearheading a 1986 boycott against Shell Oil for its ties to the country, and led a successful 10-month strike against the Pittston coal company over workers’ health care and pension funds.

Launched in April 1989, the strike drew national support from labor groups and religious leaders, with miners and their allies staging mass sit-ins to block coal trucks. Some 4,000 workers were arrested at demonstrations that turned violent at times, although Mr. Trumka said he advocated tactics that were peaceful, if nonetheless aggressive; bent nails were used on roads to block replacement workers from arriving.

“We did civil disobedience,” he told the Wall Street Journal in 2009. “You want to talk about violence? You ever see somebody die from black lung?! Everybody in my family died from black lung. They let my dad, my grandfather, breathe coal dust when they knew it would kill them. And they violently died.”

In a phone interview, his friend Robert Bruno, a labor scholar at the University of Illinois at Chicago, said Mr. Trumka “knew his history, and he went back to history,” employing strike tactics once used by labor organizers such as Mother Jones and John L. Lewis. But he added that Mr. Trumka was also a conciliator, helping to heal divisions in the labor movement and overcome racial barriers, including when he rallied support for Barack Obama in the 2008 presidential election.

Delivering a speech at a steelworkers convention that year, Mr. Trumka had what Post journalist Alec MacGillis described as “his YouTube moment, surely the first YouTube moment in the history of the perpetually sepia-tinged American labor movement.”

A video of the speech showed Mr. Trumka wagging a finger as he declared that “there is not a single good reason for any worker, especially any union member, to vote against Barack Obama. And there’s only one really, really bad reason to vote against Barack Obama. And that’s because he’s not White.”

He went on to recount a visit to his hometown of Nemacolin, in southwestern Pennsylvania, where he met a woman who told him she couldn’t trust Obama “because he’s Black.”

“Look around this town,” Mr. Trumka told her. “Nemacolin’s a dying town. There’s no jobs here. Our kids are moving away because there’s no future here. And here’s a man, Barack Obama, who’s going to fight for people like us, and you want to tell me that you won’t vote for him because of the color of his skin?” He paused. “Are you out of your ever-loving mind, lady?”

Richard Louis Trumka was born in Nemacolin on July 24, 1949. His mother was a homemaker, and at age 19 he followed his father into the mines, working his way through college and law school.

Mr. Trumka graduated from Pennsylvania State University in 1971 and received a law degree from Villanova University three years later. He joined the UMW as a lawyer and in 1982 was elected president, becoming its youngest-ever leader at age 33.

Later that year he married Barbara Vidovich, a coal miner’s daughter. Their son, Rich Trumka Jr., is a lawyer for the House Committee on Oversight and Reform. Biden nominated him last month to a seat on the Consumer Product Safety Commission.

In addition to his wife, of Rockville, Md., and son, of Olney, Md., survivors include three grandchildren and a sister.

Mr. Trumka joined the AFL-CIO’s top ranks in 1995, when he was named secretary-treasurer. In a bitter campaign for the Teamsters presidency the next year, he backed Ron Carey, a firebrand reformer, in his successful reelection bid over James P. Hoffa, who was trying to reclaim the leadership position once held by his father, Jimmy Hoffa.

A federal union overseer moved to overturn Carey’s victory, asserting that the labor leader and his aides were involved in an illegal fundraising scheme. Prosecutors suggested that Mr. Trumka had improperly funneled $150,000 in AFL-CIO funds to the Carey campaign; he took the Fifth, declining to answer questions about the case, and was not charged with wrongdoing.

“Our members don’t care about that,” he told the New York Times in 2009, dismissing a reporter’s question about the case. “They care about who’s going to fight for them to help them with their jobs and their paychecks.”

Before being elected AFL-CIO president, Mr. Trumka led an effort to use union pension funds to pressure companies on issues such as executive pay. He succeeded his longtime boss John J. Sweeney, whose retirement paved the way for Mr. Trumka’s election. Sweeney died in February.

“The lack of jobs is the first issue,” Mr. Trumka told the Catholic News Service in 2010, outlining the problems facing American workers. “The second issue is just like it: How do you make a job a good job? You make it a good job by unionizing and having collective bargaining, so that the profits made from those workers is actually shared more equitably.”