Sen. Cory Booker, D-N.J., claimed he did not know much about Demand Justice, a left-wing group that seeks to expand the Supreme Court, despite having spoken at its events in the past.

"I honestly don’t know that much about them," Booker told Politico in a report published Tuesday. "If you pick the ACLU, or the [Center for American Progress], those are groups that we’ve worked with."

"They’re not to us what the Heritage Foundation and the Federalist Society are to" Republicans, added Booker, who is a member of the Senate Judiciary Committee.

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Sen. Cory Booker, D-N.J., arrives at the Senate chamber at the Capitol in Washington, Wednesday after bipartisan congressional talks on overhauling policing practices ended without an agreement.

Sen. Cory Booker, D-N.J., arrives at the Senate chamber at the Capitol in Washington, Wednesday after bipartisan congressional talks on overhauling policing practices ended without an agreement. (AP Photo/J. Scott Applewhite)

After former Supreme Court Justice Anthony Kennedy announced his retirement in June 2018, Booker joined other Democratic lawmakers in speaking at a Demand Justice rally in front of the court building.

"We have to face a reality coming at us where we might lose some of the most precious ideals of our country," Booker said at the time. "I stand here to say, ‘This will not happen without a fight.’"

Earlier that same month, he spoke at a Demand Justice rally in front of the Capitol in protest of Trump judicial nominee Thomas Farr.

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Demand Justice has openly expressed an intention to overhaul the federal court system to advance liberal goals. Demand Justice is part of the broader network, specifically "a front for the Sixteen Thirty Fund," which Politico cited as an example of the left embracing "dark money" tactics.

Senate Minority Leader Chuck Schumer, D-N.Y., after a weekly caucus meeting at the U.S. Capitol in Washington, D.C., U.S., on Tuesday, July 10, 2018.

Senate Minority Leader Chuck Schumer, D-N.Y., after a weekly caucus meeting at the U.S. Capitol in Washington, D.C., U.S., on Tuesday, July 10, 2018. (Andrew Harrer/Bloomberg via Getty Images)

Because the Sixteen Thirty Fund is a so-called dark money group, the donors who fund it and Demand Justice are unknown.

"They want to add seats to the Supreme Court, they want to add term limits for justices, they want to overhaul it and swing not just the Supreme Court but all levels of the judiciary more progressive," Caitlin Sutherland, executive director of conservative-leaning Americans for Public Trust, told Fox News last April.

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Jackson was on Demand Justice's shortlist for potential Supreme Court nominees.

Supreme Court nominee Ketanji Brown Jackson testifies during her Senate Judiciary Committee confirmation hearing on Capitol Hill in Washington, D.C., on Tuesday, March 22, 2022.

Supreme Court nominee Ketanji Brown Jackson testifies during her Senate Judiciary Committee confirmation hearing on Capitol Hill in Washington, D.C., on Tuesday, March 22, 2022. (AP Photo/Andrew Harnik)

"She is a former public defender and Sentencing Commission vice chair, and on the federal bench, she has stood up for the rule of law, holding the Trump administration accountable for its rule-breaking," Demand Justice wrote in praise of Jackson on its website.

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Booker's office did not immediately respond to request for comment.

Fox News' Adam Shaw, Evie Fordham and Tyler Olson contributed to this report.