A woman who has accused Supreme Court nominee Brett Kavanaugh of sexual assault when they were teenagers went public with her name for the first time on Sunday, injecting immediate uncertainty into Republicans’ push to quickly confirm the next high-court justice.

The public allegation by the woman, Christine Blasey Ford, in an article published by the Washington Post Sunday, threatened to alter the trajectory of a confirmation process that has been heading toward a vote in the Senate Judiciary Committee on Thursday. A spokesman for the committee’s chairman, Sen. Chuck Grassley (R., Iowa), said Sunday that the vote would proceed as scheduled, but hours later, Sen. Jeff Flake (R., Ariz.), who sits on the committee, said he wouldn’t vote for Judge Kavanaugh to advance to the full Senate until the committee had heard from Mrs. Ford.

“I would not vote yes until we hear more from the woman who’s come forward,” Mr. Flake said in an interview. With Republicans holding just a one-vote majority on the committee, a defection by Mr. Flake would prevent the panel from favorably advancing Judge Kavanaugh to the full Senate, where the GOP has a 51-49 majority. Sen. Bob Corker (R., Tenn.) told Politico he also supported delaying the vote to hear from Mrs. Ford, while Sen. Susan Collins (R., Maine) told CNN she was discussing the matter with colleagues.

Mrs. Ford, in the Post article, said that when she and Judge Kavanaugh were teenagers at a party in the Washington, D.C., area, he and a friend pulled her into a bedroom. Judge Kavanaugh pinned her down on the bed, groped her and attempted to remove her clothing before she escaped, Mrs. Ford said in the article.

Mrs. Ford, who is a professor at Palo Alto University in California, described the episode as aggressive. “I thought he might inadvertently kill me,” she told the Post.