The strongest and loudest supporter of union construction, U.S. Department of Labor Secretary Marty Walsh, announced his intention to step down from his current position in mid-March.

Walsh, 55, the former Mayor of Boston and Massachusetts state representative, will become the first traditional Cabinet secretary to leave since President Joe Biden took office.

The former leader of the Greater Boston Building Trades Unions and a card-carrying member of Laborers Local 223 is returning to organized labor via professional sports.

In mid-February, the NHL Players’ Association (NHLPA) announced that Walsh was unanimously appointed to lead the union. He will replace outgoing Executive Director Donald Fehr.

In a statement on Twitter, Walsh, wrote that he will leave the DOL with a deeper understanding of why working people are the heart and soul and strength of our nation.

Prior to the announcement, Walsh wrote a letter to Labor Department staff and expressed his gratitude for the opportunity to serve the American workforce.

“As someone who grew up in an active union family and is a card-carrying union member, serving as Secretary of Labor and being given this unique opportunity to help working people is itself a privilege,” he wrote. “But to do so for the most pro-worker and pro-union President and administration in our nation’s history has been the ultimate honor. I am forever grateful to President Biden not only for the faith he placed in me, but for his steady, transformative and historic leadership on behalf of working people everywhere.”

President Biden praised Walsh in a prepared statement.

“My dad used to say that a job is about a lot more than a paycheck, it’s about dignity and it’s about respect,” Biden said. “Few people understand that more than Marty. I thank Marty for his work, which has made life better for millions of working Americans and will serve as a model for all future labor secretaries who truly value American working people.”

As Secretary for the Department of Labor, Walsh played a high-profile role in the Biden administration’s interactions with organized labor.

Last September, Walsh brokered a temporary labor deal between freight rail carriers and unions that was eventually settled by a vote of Congress. He visited the West Coast as port workers renegotiated their CBA with employers. He also visited many building trades union halls and training centers – including multiple stops in Ohio.

Also under his tenure, the DOL announced a plan to rescind all Industry Recognized Apprenticeship Programs (IRAPs), which were created during the Trump administration. The new type of apprenticeship model lacked the oversight and regulation required for traditional registered apprenticeship programs.

Walsh was part of the most union-friendly presidential administration in recent history. In the two years that Walsh served under President Biden, the administration enacted an executive order that required Project Labor Agreements on most federally funded projects with a $35 million or higher price tag.

As he leaves office, the DOL has yet to provide details related to a proposed rule that would expand the number of workers eligible for overtime pay; updates to the federal Davis-Bacon requirements; and a final rule redefining worker misclassification, which is expected to include more extensive limits on how workers can be considered independent contractors.

According to ESPN, Walsh, who is not an attorney, beat out former Vancouver Canucks general manager Mike Gillis; Mathieu Schneider, a former NHL defenseman and currently the assistant to the executive director under Fehr; and player agent Allan Walsh.

The seven-member committee of NHL players who were tasked with selecting a candidate, wanted someone who had not been involved in hockey labor talks in order to bring fresh ideas to the landscape, ESPN reported.

“I am honored to have been selected as the Executive Director of the NHLPA,” said Walsh in a prepared statement released by the NHLPA. “In accepting this offer I am committing to do all that I can to advocate on players’ behalf. My years of experience in the labor movement and in public life has taught me that the job is never about me. It’s about us. It’s about the people we serve. So I look forward to working with players and the NHLPA staff to make the NHLPA the best and most effective team we can be to advance and protect the interests of our players and their families.”

Deputy Labor Secretary Julie Su, who oversaw the rollout of California’s gig work law, was named the acting head of the DOL and has also been announced as Biden’s nomination to replace Walsh fulltime.