President Biden on Tuesday nominated Julie Su to be the next labor secretary, elevating a longtime advocate for workers to implement a key part of the administration’s agenda.

Julie Su

Currently the Labor Department’s deputy secretary, Su quickly emerged as a clear favorite of organized labor and the Democratic Party establishment in recent weeks after Marty Walsh resigned from the post to head the National Hockey League’s players’ union. Before assuming her current role, Su served as labor secretary in California for seven years, where she earned a reputation as a fierce advocate for immigrants and low-wage workers. She was also an architect of a controversial law that addressed the classification of workers as independent contractors but received pushback from Uber, Lyft and other tech companies.

While Su was long considered the favorite for the post, the administration also considered other potential candidates, including flight attendant union president Sara Nelson, who had the backing of Sen. Bernie Sanders, I-Vt., chair of the Senate committee that oversees labor. The decision will be cheered by labor advocates but will probably be strongly resisted by congressional Republicans, who could try to block her nomination in the Senate. Democrats control the Senate, but only by a narrow two-vote margin, giving centrist party members potential leverage over her position.

“Julie has spent her life fighting to make sure that everyone has a fair shot, that no community is overlooked, and that no worker is left behind,” Biden said in a statement. “Over several decades, Julie has led the largest state labor department in the nation, cracked down on wage theft, fought to protect trafficked workers, increased the minimum wage, created good-paying, high-quality jobs, and established and enforced workplace safety standards.”

If confirmed, Su would succeed Walsh, who led the Labor Department at the start of the Biden administration and announced in February that he was stepping down to head the NHL Players’ Association.

Biden has vowed to be the most pro-union president in U.S. history, making the position of labor secretary a crucial post in executing his policies. Su had a role in navigating the administration through a high-profile standoff with rail workers who threatened to strike over sick time, and the Labor Department will be at the center of crafting administration policy on cracking down on child labor and creating an overtime pay rule for workers, among other policies.

Some congressional Republicans reacted on Tuesday with skepticism. Sen. Bill Cassidy, R-La., the top Republican on the Senate committee overseeing the Labor Department, pointed to fraudulent unemployment payments made in California during the pandemic while Su oversaw the state’s unemployment insurance office. (White House spokeswoman Olivia Dalton, speaking to reporters on Air Force One on Tuesday, said that Su helped California process urgent claims despite “fragile, outdated technology” and that at the Labor Department, Su had “worked with states to set a big table national approach to these issues because they are a national problem.”) Cassidy also criticized the Labor Department’s proposed guidelines that would reclassify many gig workers as employees, which conservatives say would reduce workers’ flexibility.

“Deputy Secretary Su has a troubling record and is currently overseeing the Department of Labor’s development of anti-worker regulations that will dismantle the gig economy,” Cassidy said in a statement. “This does not inspire confidence in her ability to hold her current position, let alone be promoted.”

The daughter of immigrants, Su is a graduate of Stanford University and Harvard Law School who was also a recipient of the MacArthur Foundation’s “Genius” Grant, the White House said in a statement. She also spent 17 years as a civil rights attorney and defended Thai garment workers who had been trafficked into the U.S., the statement said. Despite recommending Nelson for the role, Sanders said in a statement that he was confident Su “will be an excellent Secretary of Labor.”