In an unprecedented move, a sitting senator plans to testify against another sitting senator in a confirmation hearing for a Cabinet post.

Senator Cory Booker (D-N.J.) will be taking questions Wednesday from the Senate Judiciary Committee about the racially charged comments and attitudes of potential Attorney General Jeff Sessions, calling the nomination a "consequential moment."

"I do not take lightly the decision to testify against a Senate colleague," Booker told CNN Monday night. "But the immense powers of the attorney general combined with the deeply troubling views of this nominee is a call to conscience."

The current Alabama senator's history includes a number of inflammatory remarks that have led to be deemed as racist by some detractors. In 1986, he went through hearings for a federal judgeship, where allegations that Sessions claimed the NAACP and ACLU were "un-American" in addition to claiming that the Ku Klux Klan was "OK, until [he] found out they smoked marijuana" and referred to a black lawmaker as "boy" on several occasions.

"I abhor the Klan and its hateful ideology," Sessions said Tuesday during his hearing in reference to the alleged remarks he made decades ago. "I never declared the NAACP was un-American."

Booker has also criticized Sessions' opposition to bipartisan criminal justice and immigration reform, criticism of the Voting Rights Act, and voting against the Violence Against Women Act because of its special protections for members of the gay community.

"I deeply understand the history of civil rights and the horrendous impact that relentless and systemic discrimination and the denial of voting rights has had on our African-American brothers and sisters," Sessions said at his confirmation hearing. "I have witnessed it. We must continue to move forward and never back. I understand the demands for justice and fairness made by our LGBT community. I will ensure that the statutes protecting their civil rights and their safety are full enforced. I understand the lifelong scars born by women who are victims of assault and abuse."

Sessions is the first of Trump's Cabinet nominations to have a Senate confirmation hearings, with his starting on Tuesday. 

"He has a posture and a positioning that I think represent a real danger to our country," Booker told MSNBC.