Kamala Harris leaned into her prosecutorial background on Thursday with a sharply worded letter to Attorney General William Barr asking if he’d like to “supplement” his earlier evasive testimony on whether President Trump had ever asked him to open an investigation into his enemies now that Trump has “called publicly for the prosecution of a former cabinet secretary.”

In a statement, Harris, the California senator who is running for the Democratic nomination in 2020, made clear she would not let Barr off the hook for the question after he refused to give a yes or no answer while testifying before the Senate Judiciary Committee last week.

“Today, the president all but confirmed that he has made such a request when he called publicly for the prosecution of a former cabinet secretary and then stated that his ‘people’ disagreed with him,” Harris wrote. “In light of the President’s deeply troubling statements, I request that you supplement your testimony and clarify your answers to my question.”

Harris’ letter comes just hours after Trump called for former Secretary of State John Kerry, who served under President Obama, to be prosecuted.

“In order for the American people to retain trust in the Department of Justice, the public must have confidence that the women and men who enforce our laws act with fairness and impartiality,” the letter continues. “Your failure to categorically respond to my question in the negative undermines that confidence.”

Harris has taken a series of steps within the past several weeks to directly address Trump. In an appearance at an N.A.A.C.P dinner on Sunday, Harris attacked Trump and Barr directly after her interrogation of the attorney general became a viral sensation.

A report in The New York Times noted it was part of a broader shift in Harris’ strategy, one that is starting to focus closer on her core career experience as a prosecutor. In a stop in Michigan the following day, the Times noted, Harris doubled down:

“Let me tell you how much our president can learn from a fourth grader!” she said. “The president of the United States of America has a profound amount of power that comes with that microphone and bully pulpit. And we can no longer have a president that uses that microphone to divide.”

While ramping up her attacks on the president just over a month before the first Democratic primary debates, Harris has indirectly sought to prosecute the case against Trump since long before she announced her 2020 plans, most notably during the latest Supreme Court hearings, where she rocketed to national attention for her intense grilling of Justice Brett Kavanaugh, Trump’s pick for the Supreme Court.

She later extended her sentiment to a passionate speech on the Senate floor:

“This should have been a search for the truth,” she said. “They should have been allowed to do their full job. But instead the White House did not allow it. This was not a search for the truth. Instead, this was about politics and raw power to push through an unfit nominee.”