Senator Chuck Schumer, Democrat of New York and the minority leader, said Thursday night that the selection of Mr. Scalia was a missed opportunity.

“President Trump has again chosen someone who has proven to put corporate interests over those of worker rights,” Mr. Schumer said. “Workers and union members who believed candidate Trump when he campaigned as pro-worker should feel betrayed.”

Mr. Scalia, 55, was nominated by Mr. Bush in 2001 to serve as solicitor of the Labor Department, but was never confirmed by the Senate, which was controlled by Democrats. Much of the fear about Mr. Scalia’s nomination was based on his opposition to a Clinton administration regulation that would have protected workers from repetitive stress injuries, which became known as the ergonomics rule. Mr. Scalia had weighed in frequently against the rule, deriding the rationale for it as “unreliable science.”

Mr. Bush eventually used a recess appointment to install Mr. Scalia in the position, effectively bypassing the Senate. He left the department in 2003 and returned to private practice.

A former subordinate of Mr. Scalia’s in the solicitor’s office, Ann Rosenthal, said she was appalled when he was nominated to the position after observing his opposition to the ergonomics rule. But she was pleasantly surprised to find him reasonable and relatively committed to protecting workers.

Ms. Rosenthal, who has since retired, recalled telling Mr. Scalia that he had far exceeded her expectations. “I have a different client now,” he responded.

Mr. Scalia represented a variety of corporate clients at Gibson, Dunn & Crutcher. In 2006, he helped Walmart triumph in a prominent fight against a Maryland law that would have required companies with more than 10,000 workers to either spend at least 8 percent of their payroll costs on health care, or pay into a state Medicaid fund.