WASHINGTON — She was nervous as anyone would be describing perhaps the worst evening of her life. Her voice at times was high, her manner deferential, even solicitous. And for a moment, it was possible to hear that 15-year-old girl trying to escape a bedroom where two older, bigger boys had terrorized her.
For a dozen days, Christine Blasey Ford was an idea rather than a person, the focal point of one of the most polarized debates in a polarized capital without anyone having seen her, met her or heard her. But on Thursday, she became a very human being, telling a terrible story in compelling terms that transformed the battle for the Supreme Court.
Her harrowing account of a sexual assault during a high school party by a drunken teenager she identified as Judge Brett M. Kavanaugh brought some women to tears and sent shudders through the White House and Republican circles as President Trump’s nomination for the high court looked increasingly in jeopardy. She came across as Everywoman — an Everywoman with a Ph.D. — at once guileless about politics yet schooled in the science of memory and psychology.
While her story had been told in print, hearing her describe being pushed down on a bed and Mr. Kavanaugh “running his hands over my body and grinding into me,” then trying to “take off my clothes” while his friend Mark Judge watched transformed the allegation into images and words difficult to disregard.
“Indelible in the hippocampus is the laughter,” she told the Senate Judiciary Committee when asked what was most searing in her memory, using a term for part of the brain, “the uproarious laughter between the two and their having fun at my expense.”
“I was underneath one of them while the two laughed, two friends having a really good time with one another,” she added.
Judge Kavanaugh, who arrived at the committee on Thursday afternoon to respond, has denied her charges and in the days leading up to the hearings, some Republicans suggested that perhaps it was a case of mistaken identity. She dismissed that categorically.
“With what degree of certainty do you believe Brett Kavanaugh assaulted you?” asked Senator Richard J. Durbin, Democrat of Illinois.
“One hundred percent,” she said.
Dr. Blasey, 51, a university professor in California who also goes by her married name Ford, went largely unrebutted. While Judge Kavanaugh has denied her account and will have a chance to testify later in the day, the Republicans in the early hours of the extraordinary hearing did not challenge her story in any meaningful way.
Senator Charles E. Grassley of Iowa, the Republican committee chairman, and the committee’s other Republicans turned over their share of the questioning to Rachel Mitchell, a career sex crimes prosecutor from Arizona. Ms. Mitchell methodically walked Dr. Blasey through her story one detail at a time, without making a particularly concerted effort to undermine it.
Interrupted in her interrogatory every five minutes to switch to the Democratic side, Ms. Mitchell never seemed to develop a train of questioning that would cause many watching to doubt Dr. Blasey. She asked whether Dr. Blasey ever flew to Australia and who paid for her polygraph test. At times, it was not clear what point she might be driving at. By the end, even Ms. Mitchell seemed to suggest that it was not particularly effective, noting that asking questions in five-minute increments was not the recommended method for interviewing sexual assault victims.
Dr. Blasey was not challenged in any extended way about the gaps in her story — that she could not remember whose house the party took place in and when precisely it happened. Nor was there much made of the fact that the three other people Dr. Blasey remembered being in the house at the time have said they remember no such event and had never seen Judge Kavanaugh behave like that.
Only outside the hearing room did any of the Republicans aggressively press those points. Senator Lindsey Graham of South Carolina told reporters that Dr. Blasey was being used by Democrats to smear Judge Kavanaugh. “Here’s what I’m more convinced of: The friends on the other side set it up to be just the way it is,” he continued. “I feel ambushed.”
As for Mr. Grassley, the only Republican who spoke at length during the hearing, he was more focused on defending how he had handled the allegations and assailing Democrats for not raising them earlier. Democrats responded with their own process complaints, arguing with Mr. Grassley about whether there should be an independent F.B.I. investigation of Dr. Blasey’s allegation.
During their own time for questions, Democratic senators mainly praised Dr. Blasey for her courage in coming forward and posed only sympathetic queries about how the event she described had affected her life. No one on either side pushed her to any degree or poked significant holes in her story. By the end of her appearance, even Mr. Grassley concluded by thanking her “for your bravery coming out.”
What made Dr. Blasey’s appearance so powerful was how uncomfortable she seemed. She seemed to have no artifice. While poised, she gave every impression of someone who did not relish the spotlight focused on her. Her hair falling in her face as she read her opening statement, she choked up as she recalled fearing that Judge Kavanaugh “was accidentally going to kill me” by covering her mouth to keep her from screaming.
She was anything but an eager participant in the Washington wars. She said apologetically that she had not understood how the process worked when she first tried to bring her allegation to the attention of the Senate, and her lawyer appeared to tell her to raise her hand when Mr. Grassley swore her in as a witness. She asked Mr. Grassley politely if it was O.K. for her to say something to him.
Beyond that, she asked for nothing other than a chance to speak and some caffeine. When Mr. Grassley asked at one point if she wanted a break, she held up a cup. “I’m O.K.,” she said, smiling broadly. “I got the coffee.”
She described how the assault haunted her for years even though she never told anyone about it for decades. She described the ordeal of the last couple weeks as she received death threats that forced her and her family to leave their home. She talked about her fear of flying and how stressful it was to take a lie-detector test.
Asked at one point about exculpatory evidence, she said, “I don’t know what exculpatory evidence is.”
At another point, she described why she was uncertain about coming forward, saying she feared she would be “personally annihilated.”
On this morning, at least, she was not.
Follow Peter Baker on Twitter: @peterbakernyt.