Education Secretary Miguel Cardona on Friday announced the resignation of the head of the federal aid office that oversees the government’s $1.5 trillion student loan portfolio amid growing calls from liberal lawmakers and advocates to oust the Trump administration holdover.

Mark A. Brown, a retired major general in the U.S. Air Force, was appointed by former secretary Betsy DeVos in 2019 for a three-year term with the option for an extension. People familiar with the matter who were not authorized to speak publicly said he had hoped to keep his position, but in recent weeks had prepared his staff for his departure.

Since the election of President Biden, Sen. Elizabeth Warren (D-Mass.) and consumer groups have encouraged him to replace Brown, who they felt was too closely aligned to DeVos and her controversial policies.

“Students deserve leadership at this office who will follow the law and make this program work for students,” Warren said in a statement Friday. “I look forward to working with Secretary Cardona to reform the FSA so that it works for student borrowers instead of big student loan servicing corporations.”

During Brown’s tenure, a federal judge slapped the Education Department with a $100,000 fine in October of 2019 for violating an order to stop collecting loan payments from former Corinthian Colleges students. At the time, Brown released a video posted to Twitter saying the agency took full responsibility for its actions.

His office also faced scrutiny last year for mismanaging a federal order halting involuntary collection for past-due student debt during the coronavirus pandemic. After borrowers sued the department in May, the agency said it was doing everything in its power to help borrowers but were stymied by employers failing to cease garnishment.

Biden has said simplifying loan forgiveness for public servants and streamlining income-driven repayment options are among his top priorities. Because the student aid office will play a key role in the administration’s plans, liberal groups say the leadership of the unit is especially important.

“Under my leadership, the Department of Education will work to strengthen college as a reliable pathway to the middle class while protecting students and loan borrowers,” Cardona said in a statement Friday. “In service to our nation’s students, the Department’s Federal Student Aid division will renew its focus on streamlining access to and management of federal financial aid, easing the burden of student debt, and carefully stewarding taxpayer dollars.”

Robin Minor, the deputy chief operating officer for partner participation and oversight, will assume Brown’s duties until a replacement is appointed. The Education Department declined to comment on whether it has identified candidates for the role.

In an email and video Brown sent to his staff Friday morning, obtained by The Washington Post, he said he “could not be prouder of FSA’s many accomplishments over the past two years.” The support of the staff, he said, “sustained my spirit even as some critics became louder and less accurate. You never lost sight of our mission so I could do nothing less.”

The student aid office provides more than $150 billion in federal grants, loans and work-study funds to college students and oversees the $1.5 trillion federal student loan portfolio. It is in the middle of overhauling the way it administers and manages student loans, a project dubbed Next Generation Financial Services Environment, or NextGen.

The project has contended with pushback from student loan companies and members of Congress who have tried to curtail the reforms. As work continues on NextGen, the student aid office must also institute new laws to make it easier to enroll in income-driven repayment plans and apply for financial aid.