UPDATE 2-U.S. Labor Secretary Walsh appointed executive director of NHL union

(Adds details on Walsh and on deputy secretary who will serve as acting head of Labor Department)

By Kanishka Singh and Nandita Bose

WASHINGTON, Feb 16 (Reuters) - U.S. Labor Secretary Marty Walsh has been named executive director of the National Hockey League Players' Association (NHLPA) and will leave his Cabinet position in mid-March, the union and the Labor Department said on Thursday.

Walsh, 55, who had been expected to step down from his labor secretary role, was recommended for the job after a nine-month search by a player-led committee, the union said.

A former Democratic mayor of Boston and president of a labor union, Walsh would be the first of President Joe Biden's Cabinet secretaries to resign since Biden took office in January 2021.

It comes amid a wider shakeup within the Biden administration as it begins the tail end of its four-year term in office and prepares for a possible re-election campaign.

"I met with President Biden and he accepted that my time as Labor Secretary will conclude mid-March," Walsh said in a note to his colleagues at the Labor Department.

"As someone who battled cancer as a child and addiction as an adult, my life has been defined by second chances, and our work delivered second chances to millions of people in this country who needed them," he said in the note.

Walsh has played a critical role in addressing some of the most complex business and union disputes and crises over Biden's first two years. These included brokering an eleventh-hour compromise in a dispute between freight rail carriers and unions that threatened to bring the economy to a grinding halt.

Once Walsh exits, Deputy Secretary Julie Su, seen as a leading contender to succeed Walsh, will take charge of DOL on an acting basis.

There is a concerted push to get Biden to appoint Su to the role both for her familiarity with the agency and labor policy. There is currently no Asian American or Pacific Islander in the Cabinet at the secretary level.

Su recently scored endorsements from the Congressional Black Caucus and the Congressional Asian Pacific American Caucus.

In his letter to DOL colleagues, Walsh called Su an "incredible leader" who "has been central to our success as a team and as a Department." (Reporting by Kanishka Singh and Nandita Bose in Washington Additional reporting by David Shepardson in Washington Editing by Jonathan Oatis and Matthew Lewis)