In interviews with The New York Times this year, several people who have worked with Mr. Acosta expressed mixed feelings of him as a colleague. Some said he was a passive leader, even using inaction to serve his interests. But others, including professors at Florida International University’s law school, said Mr. Acosta was unbiased and did not let his political views color his professional decisions.

Facing the Senate Health, Education, Labor and Pensions Committee in March, Mr. Acosta defended himself against Democrats who voiced concerns that he might allow conservative political ideologues to shape the department. He assured them that he would put the interest of workers first.

“As a former prosecutor, I will always be on the side of the law and not any particular constituency,” he told senators.

Senator Lamar Alexander, Republican of Tennessee and the committee’s chairman, said that Mr. Acosta “understands how a good-paying job is critical to helping workers realize the American dream for themselves and for their families.”