WATCH: Cory Booker’s Testimony Against Jeff Sessions

While sitting next to civil rights legend John Lewis, New Jersey Senator Cory Booker became the first sitting senator to testify against a colleague seeking a cabinet position. He testified against Donald Trump‘s nomination of Alabama Senator Jeff Sessions to be his attorney general.

Sessions spent much of his time during the first day of hearings before the Senate Judiciary Committee responding to accusations of racism levied against him. However, Booker made his case for why he didn’t think Sessions was right for the job.

At the start of his testimony, Booker explained why he believed it was so important to break Senate norms and testify against a colleague. “I believe, like perhaps most of my colleagues in the Senate, that in the choice between standing with Senate norms or standing up for what my conscious tells me is best for our country, I will always chose conscious and country,” he said.

He also said that there was a “mutual respect” between himself and Sessions, even though they often disagree on issues. He cited their work together to co-sponsor a bill to give the Congressional Gold Medal to civil rights marchers.

“I want an attorney general who is committed to supporting law enforcement and securing law and order, but that is not enough,” Booker said. “America was founded on not law and order, but justice for all and critical to that is equal justice under the law. Law and order without justice is not unobtainable.”

Booker went on to argue that Sessions would not protect civil rights as head of the justice department.

“Senator Sessions’ record does not speak to that desire, intention or will,” Booker said. “With all that at stake in our nation now, with the urgent need for healing and live, I pray that my colleagues will join me in opposing his nomination.”

It’s not likely that Booker’s testimony will stop Sessions from being confirmed as attorney general, but the testimony will help Booker raise his profile. After his praised DNC speech, he’s been at the center of speculation for a possible 2020 presidential run.