WASHINGTON - U.S. Senator Kamala Harris on Tuesday urged a House of Representatives panel to investigate Supreme Court Justice Brett Kavanaugh, while a Democratic lawmaker filed an impeachment resolution in the wake of new allegations of sexual misconduct by the conservative judge when he was in college in the 1980s.

The moves by Harris, one of 20 Democratic presidential candidates, and Representative Ayanna Pressley, a progressive on the left of the party, signaled impatience among some Democrats with congressional leaders unenthusiastic about pursuing Kavanaugh's impeachment, though their efforts appeared unlikely to spur action.

Harris said in a letter to House Judiciary Committee Chairman Jerrold Nadler that the panel should "hold Mr. Kavanaugh accountable for his prior conduct and testimony."

Nadler on Monday faulted the FBI's probe of prior sexual misconduct allegations against Kavanaugh ahead of his narrow confirmation by the Senate in October 2018, saying in a radio interview it "apparently was a sham." But Nadler also said his panel had its "hands full" with investigating Republican President Donald Trump.

In her letter to Nadler, Harris suggested the House Judiciary Committee could create a task force and retain outside counsel if it did not have the time or resources to pursue an inquiry of Kavanaugh now.

Harris and several other Democratic presidential candidates called for Kavanaugh's impeachment after the New York Times published an essay over the weekend detailing what it described as a previously unreported incident of sexual misconduct by Kavanaugh.

Others include former U.S. Housing and Urban Development Secretary Julian Castro; U.S. Senators Elizabeth Warren and Cory Booker; South Bend, Indiana Mayor Pete Buttigieg; and former U.S. Representative Beto O'Rourke.

Front-runner Joe Biden, the former vice president, stopped short of advocating impeachment, instead backing a probe of how the FBI handled its investigation.

Warren told reporters on Tuesday that she believed "the only tool available" to investigate Kavanaugh further is an impeachment proceeding.

Pressley's resolution in the House called for Nadler's committee to launch an impeachment inquiry, and said the panel could create a task force or hire consultants if necessary.

Pressley is one of four progressive House Democrats often referred to as "The Squad."

Pressley's resolution and Harris' letter are unlikely to spark results. Calls to impeach Kavanaugh have received a lackluster response from Democratic congressional leadership, most of whom maintain that Democrats should focus on issues and legislation, not impeachments.

House Speaker Nancy Pelosi has made no comment on the recent allegations against Kavanaugh. Senate Democratic Leader Chuck Schumer sidestepped a question Tuesday about whether an impeachment probe should be launched against the justice, saying: "I never thought Kavanaugh should be on the bench and I still don't today."

Questions for FBI Director

Trump and other Republicans likewise rejected pursuing Kavanaugh's impeachment. Trump encouraged Kavanaugh, whose appointment cemented the Supreme Court's 5-4 conservative majority, to sue for libel. Vice President Mike Pence said on Tuesday that "the calls by Democratic candidates for president to remove Justice Kavanaugh from the court are a disgrace."

The New York Times reported that the FBI had knowledge of the additional allegation but did not investigate it thoroughly, Harris wrote in the letter to Nadler. She encouraged Nadler to examine the agency's handling of the matter, and also whether Kavanaugh was truthful during his confirmation hearings.

Nadler said on Monday that FBI Director Christopher Wray would face questions about the agency's investigation into Kavanaugh when Wray appears before the committee next month.

No Supreme Court justice has ever been ousted through the impeachment process outlined in the U.S. Constitution, in which the House initiates proceedings and the Senate then holds a trial on whether to remove an individual from office. The only justice ever impeached in the House was spared by the Senate in 1804.