Democrats questioning Pam Bondi, President-elect Donald J. Trump’s pick for attorney general, at her confirmation hearing are heavily focusing on how, or even if, she would ensure the independence of the Justice Department’s criminal investigations.

Senator Chris Coons of Delaware, a Democrat, asked Ms. Bondi if she would drop a case if the White House objected to it. She responded that she would not have accepted the nomination if she thought that could happen.

But it has occurred before under Mr. Trump: During his first administration, he suggested to James B. Comey, then the F.B.I. director, that he drop an investigation of his national security adviser. Mr. Comey did not intervene in the case and was later fired.

Senator Lindsey Graham advised Mr. Trump to pick Ms. Bondi, who is an unapologetic advocate for Mr. Trump. In the hearing, he brushed aside concerns that a close relationship with the president-elect will compromise her ability to execute her duties. He said it was most likely an asset.

“That’s probably why President Kennedy picked his brother” to run the Justice Department, he quipped.

During the hearing, Ms. Bondi repeatedly circled back to her argument that the Justice Department has been misused and misdirected by politically motivated decision-makers, suggesting it goes way beyond the investigations and prosecutions of Mr. Trump.

“Politics has to be taken out of this system,” she said. “This department has been weaponized for years and years and years, and it has to stop.”

Pressed by Senator Sheldon Whitehouse, Democrat of Rhode Island, about her past vow to “prosecute the prosecutors,” Ms. Bondi said “none of us are above the law.” As an example of bad conduct within the Justice Department, she cited the case of an F.B.I. lawyer who pleaded guilty for doctoring an email related to an intelligence surveillance court order on a former Trump adviser in 2017.

After Mr. Trump was indicted in Georgia by the Fulton County district attorney with 18 others on accusations of orchestrating a “criminal enterprise” to reverse the results of the 2020 election in the state, Ms. Bondi declared on Fox News that in the next Republican administration, “the Department of Justice, the prosecutors will be prosecuted, the bad ones.” She added, “The investigators will be investigated.”

In the recent past, nominees for attorney general have pledged to ensure that the department adheres to the post-Watergate tradition of keeping the White House out of criminal investigations. Ms. Bondi, however, would be the first attorney general to enter the job after a Supreme Court ruling last summer that explicitly approved of the president overseeing the Justice Department’s investigative work.

“The president may discuss potential investigations and prosecutions with his attorney general and other Justice Department officials to carry out his constitutional duty ‘to take care that the laws be faithfully executed,’” Chief Justice John G. Roberts Jr. wrote for the majority in the decision on presidential immunity that significantly expanded the executive’s power.