WASHINGTON -- U.S. Supreme Court nominee Brett Kavanaugh could sit in judgment of the president who picked him, an important reason to oppose his nomination, according to U.S. Sen. Cory Booker.

Booker, a member of the Senate Judiciary Committee that will hold hearings on Kavanaugh next month, reiterated his opposition to his nomination after meeting with the judge.

He said Kavanaugh, a judge on the U.S. Court of Appeals, "refused to commit to recusing himself" from cases involving special counsel Robert Mueller's investigation into collusion between Russia and President Donald Trump's campaign and "has already reached the legal conclusion that a sitting president should not be investigated or indicted while in office."

"It's clearer than ever that Judge Kavanaugh will not be an independent check on this president," said Booker, D-N.J.

U.S. Sen. Robert Menendez, D-N.J., also has said he will vote against Kavanaugh's nomination.

Booker earlier asked the Judiciary Committee to delay action on Kavanaugh until after Muller's investigation.

"At a moment in history when the president has been directly implicated in a federal crime, the Senate should not be acting to advance the confirmation of a Supreme Court justice who could ultimately rule to shield President Trump from accountability," Booker said.

Booker also suggested that Kavanaugh would provide the fifth vote to overturn Roe v. Wade, the landmark Supreme Court case that legalized abortion.

Trump promised during the campaign to appoint justices who would overturn the decision, a long-sought goal of the Christian conservatives who strongly supported him.

"Judge Kavanaugh was unable to assure me that he believes Roe v. Wade is correctly decided Supreme Court precedent, which further reinforces that his confirmation would be a direct threat to a woman's right to make her own medical decisions," Booker said.

Booker will get to question Kavanaugh when the Judiciary panel holds hearings on his nomination beginning Sept. 4.

In yet another departure from legislative norms, Senate Republicans are rushing ahead with Kavanaugh's nomination before receiving the documents lawmakers have sought about his past government service, including his time in President George W. Bush's administration.

The National Archives has said it won't be able to provide all of the material until late October.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.