WASHINGTON — Democratic efforts to highlight sexual assault charges that are more than 30 years old have been dismissed by supporters of Judge Brett M. Kavanaugh as the dredgings of ancient history. But the judge’s response to those accusations has raised new issues that go to the core of who President Trump’s Supreme Court nominee is right now: his truthfulness, his partisanship and his temperament.
For Democrats determined to derail Judge Kavanaugh, his performance last week before the Senate Judiciary Committee — his dissembling about his teenage years; his playing down drinking in high school and college; his raw, angry emotions; and his broadsides against Democratic questioners — is proving to be a new avenue of attack, if the accusations of sexual assault are not enough to swing the votes of three key Republicans and two undecided Democrats.
“The issues of credibility and temperament are not something that happened 30 years ago; they’re about Judge Kavanaugh today and how he is as a 53-year-old,” Senator Chuck Schumer of New York, the Democratic leader, said in an interview on Monday, giving a hint of the Democrats’ strategy. “I think there are serious questions about both his credibility and his temperament that may, to some senators, be more important than the activities that occurred in high school.”
As the investigation of past actions continues, lawmakers in both parties are parsing Judge Kavanaugh’s testimony from last week. At least one undecided Republican, Senator Jeff Flake of Arizona, took issue on Monday with the nominee’s angry treatment of Democrats who questioned him about his drinking in high school. Judge Kavanaugh parried a question from Senator Amy Klobuchar, Democrat of Minnesota, about whether he had ever blacked out from drinking — not by answering the question, but by asking the senator if she had ever blacked out. He later apologized.
His opening statement suggested the inquiry into Christine Blasey Ford’s sexual assault allegation was motivated by Democratic bitterness over the 2016 election and his role in the investigation of President Bill Clinton.
“I didn’t like some of the more partisan references and the tone, particularly with some of my colleagues,” Mr. Flake told an audience in Boston, singling out Judge Kavanaugh’s treatment of Ms. Klobuchar. But he said he might have been similarly angry if he had stood accused of sexual assault.
Republicans are coming to the judge’s defense over what they say was his understandable indignation.
“I would defy anyone not to be angry about that if they believe the allegations against them were completely false,” said Senator John Cornyn of Texas, the No. 2 Republican in the chamber, adding: “He became very emotional as he choked back tears. But I must say, he wasn’t the only one choking back tears during his defense of his good name and his reputation.”
Judge Kavanaugh’s allies say Democrats are raising issues of character because they know the F.B.I. will not be able to prove allegations of sexual assault.
“This is another part of their moving the goal posts, which is happening at the speed of light at this point,” said Carrie Severino, the chief counsel for the Judicial Crisis Network, a conservative advocacy group.
But the undecided senators — Mr. Flake, Lisa Murkowski of Alaska and Susan Collins of Maine, all Republicans, and Heidi Heitkamp of North Dakota and Joe Manchin III of West Virginia, both Democrats — are keeping an open mind. Ms. Murkowski told CNN, “In my view, the F.B.I. needs to be free to do its job as the investigating body.”
Mr. Manchin offered perhaps a hint of the way he is leaning when he tweeted on Monday evening: “No man can understand the trauma that women feel from a sexual assault. My heart goes out to the brave survivors who have the courage to come forward and share their story.”
The battle over Judge Kavanaugh is playing out in the middle of a midterm election campaign that has energized Democratic women across the country, against the backdrop of the #MeToo movement. For both the judge, and the nation, the stakes are high: If confirmed, Judge Kavanaugh would replace the retired Justice Anthony M. Kennedy, the swing vote on a deeply divided court. He is young enough, 53, that he could shape American jurisprudence for decades to come.
Judge Kavanaugh came up in Washington through partisan politics; he worked on the investigation that led to Mr. Clinton’s impeachment, and later he worked for President George W. Bush. At his first Supreme Court confirmation hearing, last month, he portrayed himself as a neutral arbiter of the law who is above politics, telling the Judiciary Committee that the Supreme Court “must never be viewed as a partisan institution.”
But last week he took the gloves off, ripping into Democrats for what he called “a calculated and orchestrated political hit, fueled with apparent pent-up anger about President Trump and the 2016 election” and “revenge on behalf of the Clintons.” Senator Mazie K. Hirono, Democrat of Hawaii and a member of the Judiciary Committee, seized on those comments on Monday as she laced into Judge Kavanaugh in a speech on the Senate floor.
“We all saw something about Judge Kavanaugh’s temperament and character that day that should disqualify him from serving on the Supreme Court of the United States,” Ms. Hirono said. “He was angry. He was belligerent. He was partisan. He went on the attack against senators questioning him. These are not qualities we look for in a Supreme Court justice, or a judge for that matter.”
But Senator Charles E. Grassley, Republican of Iowa and the Judiciary Committee chairman, said Judge Kavanaugh could be excused for showing passion. Mr. Grassley said he was reminded of the 1991 testimony of Clarence Thomas, who told the committee that the hearing into sexual harassment allegations from Anita F. Hill amounted to a “high-tech lynching.”
“I don’t think what he said is any different than what Justice Thomas said,” Mr. Grassley said. He added of Justice Thomas, “He’s been on the Supreme Court for 26 years, and I’ve never heard anybody raise any questions about his temperament, and it’s seemed to me to be just as dogmatic and as explosive as what he said.”
Nicholas Fandos contributed reporting from Washington, and Robin Pogrebin from New York.