Supreme Court nominee Judge Brett Kavanaugh speaks in the East Room of the White House in Washington, July 9, 2018. Jim Bourg | Reuters

Judge Brett Kavanaugh, President Donald Trump's nominee for the Supreme Court, in 2016 said that he would "put the final nail" in a 1988 high court ruling that upheld the law authorizing independent counsel prosecutors, according to a video that came to light Wednesday. Democratic senators immediately seized on the video to demand that Kavanaugh, at the least, promise to recuse himself from any case related to special counsel Robert Mueller, who is investigating Trump presidential campaign. Trump has repeatedly called Mueller's probe a "witch hunt." Meanwhile, a new poll shows that Kavanaugh's support from the public is narrower than usual for a Supreme Court nominee, another detail that could point to a tough confirmation process for the judge. Those criticisms came a day after a new Pew Research Center poll showed that just 41 percent of Americans support Kavanaugh's confirmation as a Supreme Court justice, compared with 36 percent who do not believe he should be confirmed. That 5 percentage-point gap is the narrowest net-postive spread for a Supreme Court pick since the 6 percentage-point edge for Harriet Miers, the White House counsel who withdrew her nomination by President George W. Bush after she flopped in interviews with a number of senators.

Democrats seize on Kavanaugh's comments

Although Mueller's office is authorized by regulations different than the law which until 1999 had authorized independent counsels to investigate government officials, Democrats fear Kavanaugh's support for a strong executive branch and a belief that a sitting president should be exempt from prosecution while still in office, could lead him to undercut Mueller's power. "We already know he believes the president shouldn't be investigated while in office — that a president can't be indicted while in office," said Sen. Chuck Schumer, D-N.Y., Senate minority leader. "Clearly, Judge Kavanaugh's judicial philosophy incorporates an almost monarchical view of executive power and accountability animated by a belief that our chief executive gets to play by a different set of rules." Schumer added: "Judge Kavanaugh, particularly after this interview, needs to recuse himself from anything having to do with the Mueller probe." Sen. Richard Blumenthal, D-Conn., said it is clear that Kavanaugh believes "the president is above the law." The White House did not immediately respond to a request for commment from CNBC.

'I would put the final nail in'

In the March 2016 video, which gained attention Wednesday after a report by CNN, Kavanaugh, currently a federal appeals court judge in Washington, D.C., appeared at an event hosted by the conservative American Enterprise Institute. During his talk, Kavanaugh said he thought Supreme Court justices "of all stripes" agree that the legal concept known as "stare decisis" — or the invocation of previously decided cases by a court to decide a pending case — was "important but not an inexorable command ... it's not absolute." He said that if courts always hewed to stare decisis then "you would have some horrible decisions still on the books." Asked on the tape if he could think of a decision that ought to be overturned, Kavanaugh gave a deadpan answer, "Yes," to audience laughter, but then said "No" when asked which decision that was. But he then continued. "Actually, I'm going to say Morrison v. Olson," Kavanaugh said. "It's been effectively overuled, but I would put the final nail in," he added. In its 1988 ruling in Morrison v. Olson, the Supreme Court, by a 7-1 margin, upheld the constitutionality of the Ethics in Government Act of 1978, which gave a special three-judge court the power to appoint an independent counsel at the recommendation of the attorney general. The court ruling found that the law did not violate the Constitution's separation of powers between the executive and judicial branches of government. The law remained in effect for 11 years after the ruling, and was famously used to appoint Kenneth Starr, the independent counsel whose probe of President Bill Clinton led to the impeachment of Clinton by the House of Representatives. Kavanaugh had been a lawyer on Starr's team for that case, which ended after Clinton was acquitted by the Senate.

Special counsels vs. independent counsels