WASHINGTON — In an extraordinary and highly emotional day of Senate testimony, California psychology professor Christine Blasey Ford quietly recounted her “100 percent” certainty Thursday that Supreme Court nominee Brett Kavanaugh had sexually assaulted her when they were teenagers. He angrily declared he was “100 percent certain” he did no such thing.

They both said the event and the public controversy that has erupted 36 years later had altered their lives forever and for the worse — perhaps the only thing they agreed on during a long day of testimony that was a study in contrasts of tone as well as substance.

The hearing was a stunning public airing of a partisan fight — charged with explosive gender politics. The future of the high court, and potentially control of Congress, hangs in the balance. Senators were left to decide whether the long day tipped their confirmation votes for or against President Donald Trump’s nominee.

Coming forward publicly for the first time, Ford quietly told the nation and the Senate Judiciary Committee her long-held secret of the alleged assault in locked room at a gathering of friends when she was just 15. The memory — and Kavanaugh’s laughter during the act — was “locked” in her brain, she said: “100 percent.”

Hours later, Kavanaugh angrily denied it, alternating a loud, defiant tone with near tears as he addressed the Senate Judiciary Committee. “You have replaced ‘advise and consent’ with ‘search and destroy,’?” he said, referring to the Constitution’s charge to senators’ duties in confirming high officials.

What happens next may hinge on what President Donald Trump and his Republican allies think about the display in what could become a defining moment for a party that has struggled to retain female voters.

Maryland Gov. Larry Hogan is among four Republican governors who called on the Senate to delay a confirmation vote on Kavanaugh until there’s an independent investigation of whether he committed one or more sexual assaults in the 1980s. Hogan is advocating for the Senate to “slow down until there’s a full investigation,” his spokeswoman, Amelia Chasse, said Thursday. Other Republican governors urging a delay are Charlie Baker of Massachusetts, John Kasich of Ohio and Phil Scott of Vermont.

But Republican senators say the Judiciary Committee plans to vote this morning on Kavanaugh’s nomination.

Sen. John Cornyn of Texas, the second ranking-Republican, had said Thursday that the GOP conference would meet and “see where we are.” After a meeting, Republican Sen. Lindsey Graham said, “There will be a vote tomorrow morning.”

A floor vote before the full Senate could occur Saturday.

Democrats repeatedly asked Kavanaugh to call for an FBI investigation into the claims. He did not.

“I welcome whatever the committee wants to do,” he said.

Republicans are reluctant for several reasons, including the likelihood that further investigations could push a vote past the Nov. 6 midterm elections that may switch Senate control back to the Democrats and make consideration of any Trump nominee more difficult.

Across more than 10 hours, the senators heard from only the two witnesses.

Ford delivered her testimony with steady, deliberate certitude. She admitted gaps in her memory as she choked back tears and said she “believed he was going to rape me.”

Kavanaugh’s entered the hearing room fuming and ready to fight, as he angrily denied the charges from Ford and other woman accusing him of misconduct, barked back at senators and dismissed some questions with a flippant “whatever.”

“You may defeat me in the final vote, but you’ll never get me to quit, never,” he said.

Trump nominated the conservative jurist in what was supposed to be an election-year capstone to the GOP agenda, locking in the court’s majority for years to come. Instead the nomination that Republicans were rushing for a vote now hangs precariously after one of the most emotionally charged hearings Capitol Hill has ever seen. Coming amid a national reckoning over sexual misconduct at the top of powerful institutions, it exposed continued divisions over justice, fairness and who should be believed.

And coming weeks before elections, it ensured that the debate would play into the fight for control of Congress.

The day opened with Ford, now a 51-year-old college professor in California, raising her right hand to swear under oath about the allegations she said she never expected to share publicly until they leaked in the media two weeks ago and reporters started staking out her home and work in California.

Wearing a blue suit as Anita Hill did more than two decades ago when she testified about sexual misconduct by Clarence Thomas, the mother of two testified before a committee that had only male senators on the Republican side of the dais.

The psychology professor described what she says was a harrowing assault in the summer of 1982: how an inebriated Kavanaugh and another teen, Mark Judge, locked her in a room at a house party as Kavanaugh was grinding and groping her. She said he put his hand over her mouth to muffle her screams. “I believed he was going to rape me,” she testified.

When the committee’s top Democrat, Sen. Dianne Feinstein of California, asked how she could be sure that Kavanaugh was the attacker, Ford said, “The same way I’m sure I’m talking to you right now.” Later, she told Sen. Dick Durbin, D-Ill., that her certainty was “100 percent.”

Asked by Sen. Patrick Leahy, D-Vt., for her strongest memory of the alleged incident, Ford, said it was the two boys’ laughter. “Indelible in the hippocampus is the laughter,” said Ford, who is a research psychologist, “the uproarious laughter between the two.”

Republican strategists were privately hand-wringing after Ford’s testimony. The GOP special counsel Rachel Mitchell, a Phoenix sex crimes prosecutor, whom Republicans had hired to avoid the optics of their all-male lineup questioning Ford, left Republicans disappointed.

Mitchell’s attempt to draw out a counter-narrative was disrupted by the panel’s decision to allow alternating five-minute rounds of questions from Democratic senators.

During a lunch break, even typically talkative GOP senators on the panel were without words. John Kennedy of Louisiana said he had no comment. Texas Sen. Ted Cruz said he was “just listening.”

Then Kavanaugh strode into the committee room, arranged his nameplate just so, and with anger on his face started to testify with a statement he said he had shown only one other person. Almost immediately he choked up. “My family and my name have been totally and permanently destroyed,” he said.

He lashed out over the time it took the committee to convene the hearing after Ford’s allegations emerged, singling out the Democrats for “unleashing” forces against him. “This confirmation process has become a national disgrace,” he said. He mocked Ford’s allegations — and several others since — that have accused him of sexual impropriety. He scolded the senators. “I’m innocent,” he said. “I’m innocent of this charge.”

Kavanaugh, who has two daughters, said one of his girls said they should “pray for the woman” making the allegations against him, referring to Ford. “That’s a lot of wisdom from a 10-year-old,” he said choking up. “We mean no ill will.”

The judge repeatedly refused to answer senators’ questions about the hard-party atmosphere that has been described from his peer group at Georgetown Prep and Yale, treating them dismissively. “Sometimes I had too many beers,” he acknowledged. “I liked beer. I still like beer. But I never drank beer to the point of blacking out, and I never sexually assaulted anyone. “

When Sen. Amy Klobuchar, D-Minn., pressed if he ever drank so much he blacked out, he replied, “Have you?” After a break in the proceedings, he came back and apologized to Klobuchar, who had said that her father was an alcoholic.

Behind him in the audience as he testified, his wife, Ashley, sat looking stricken.

Republicans who had been scheduled to vote as soon as today at the committee — and early next week in the full Senate — alternated between their own anger and frustration at the allegations and the process.

“You’re right to be angry,” said Sen. John Cornyn, R-Texas. Sen. Lindsey Graham, his voice rising in anger, called the hearing the “most unethical sham since I’ve been in politics.”

Marc Short, the former White House liaison to Congress, predicted that Kavanaugh’s impassioned testimony would help him win confirmation along party lines.

President Donald Trump was heartened by the fiery testimony, aides said. One senior administration official involved in the confirmation process described Kavanaugh’s performance as “powerful . strong . game changing” in a text message. The president was “happier” to see Kavanaugh defending himself so strongly, another administration official said, as Trump counseled Kavanaugh to do earlier in the week after the nominee and his wife appeared on Fox News.

Baltimore Sun reporter Luke Broadwater contributed to this article.