Biden, in a statement on Tuesday, called her a “champion for workers”.

“Julie is a tested and experienced leader, who will continue to build a stronger, more resilient, and more inclusive economy that provides Americans a fair return for their work and an equal chance to get ahead,” he said.

“She helped avert a national rail shutdown, improved access to good jobs free from discrimination through my Good Jobs Initiative, and is ensuring that the jobs we create in critical sectors like semiconductor manufacturing, broadband and healthcare are good-paying, stable and accessible jobs for all.”

Su was considered to lead the department when Biden won the White House but instead became the department’s deputy.

Walsh announced his intention to leave the administration earlier this month to lead the National Hockey League Players’ Association. Su will serve as the acting secretary until the Senate acts on her nomination.

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Biden had been under pressure from the Congressional Asian Pacific American Caucus and other Asian-American and Pacific Islander advocates to select Su to head the department.

This administration was the first in more than two decades to not have a Cabinet secretary of AAPI descent, despite its regular declarations that it was the most diverse in history. Vice-President Kamala Harris and US Trade Representative Katherine Tai are of AAPI descent but do not lead a Cabinet department.

Su, if confirmed, would also expand the majority of women serving in the president’s Cabinet. She was confirmed by the Senate to her current role in 2021 by a 50–47 vote.

Su’s nomination drew swift support from Democrats on Capitol Hill, with Senate Majority Leader Chuck Schumer saying she would be “phenomenal” in the job.

“The president couldn’t have picked a better nominee,” he told reporters. “I’m really excited about her, and we’re going to move to consider her nomination very, very quickly.”

Senator Bernie Sanders, who will preside over Su’s confirmation hearing as chair of the Senate health, education, labour and pensions committee, praised the selection. Sanders had urged consideration of Sara Nelson, the president of the flight attendants union, but made clear Su had his strong support.

“I’m confident Julie Su will be an excellent Secretary of Labor,” he tweeted. “I look forward to working with her to protect workers’ rights and build the trade union movement in this country.”

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In a tweet, congresswoman Judy Chu, who chairs the Congressional Asian Pacific American Caucus, praised the selection and thanked Biden for “nominating your first AAPI Cabinet Secretary!”

“I am elated that President Biden is nominating Julie Su to be our nation’s next Labor Secretary,” Chu wrote. “She’s eminently qualified to lead the Department and will successfully deliver results for our workers on Day 1.”

Her nomination also comes at a key moment for labour unions, which have been facing a decline in membership for decades. Unions gained some momentum as workers at major employers such as Amazon and Starbucks pushed to unionise.

But Biden – an avowed pro-union president – had to work with Congress to impose a contract on rail workers last year to avoid a possible strike.

The Labour Department said just 10.1 per cent of workers last year were union members. That figure has been cut nearly in half since 1983 and could fall further, as younger workers are less likely to belong to unions.