The Senate confirmed Pam Bondi as attorney general on Tuesday evening, putting in place a steadfast loyalist to President Trump to oversee a Justice Department he has bitterly denounced.

Ms. Bondi, 59, was confirmed by a vote of 54 to 46, with one Democrat, John Fetterman of Pennsylvania, joining the Republican majority.

A former prosecutor in Florida, Ms. Bondi, 59, has acted as a high-profile surrogate for Mr. Trump. She cast doubt on the results of the 2020 election, criticized prosecutors in other jurisdictions who charged Mr. Trump with crimes and defended him at his first impeachment, over whether he had improperly withheld military aid to Ukraine.

She takes the reins as the president has tossed vague accusations of criminal wrongdoing at his political rivals, and out-of-power Democrats warn that as attorney general, she may enable abuses of power.

Mr. Trump had made plain his intent to install an ally as the nation’s chief law enforcement officer, vowing to eliminate what he calls his “deep state” rivals. The pledge has raised the possibility that he would seek to end a longstanding practice of Justice Department criminal investigations operating independent of White House direction.

The department has already begun making sweeping personnel changes in the career ranks — reassigning or dismissing scores of prosecutors, including those involved in the investigations into Mr. Trump.

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