Updated at 5:22 p.m.

The confirmation of U.S. Supreme Court nominee Brett Kavanaugh hit a snag Friday when a key Republican senator said he would not feel comfortable casting a final vote without a limited investigation by the FBI into sexual assault allegations against the Trump administration's nominee.

Although the Senate Judiciary Committee sent Kavanaugh's nomination to the full Senate on a 11-10 party-line vote, the move by Sen. Jeff Flake, R-Arizona, in coordination with committee Democrats, could put Kavanaugh's nomination in peril if Senate Majority Leader Mitch McConnell does not agree to delay the floor vote for up to one week.

Flake said the delay would allow the FBI to conduct any further inquiry into the sexual assault allegation by Dr. Christine Blasey Ford, the California professor who testified Thursday that Kavanaugh sexually assaulted her at a house party in the 1980s. President Trump said in a statement Friday evening: “I've ordered the FBI to conduct a supplemental investigation to update Judge Kavanaugh's file. As the Senate has requested, this update must be limited in scope and completed in less than one week.”

Kavanaugh said in a statement: “Throughout this process, I've been interviewed by the FBI, I've done a number of 'background' calls directly with the Senate, and yesterday, I answered questions under oath about every topic the Senators and their counsel asked me. I've done everything they have requested and will continue to cooperate.”

The Senate is divided—51 Republicans and 49 Democrats—and a simple majority is needed for confirmation. “This is ripping the country apart,” Flake said Friday afternoon. “We ought to do what we can to make sure we do all due diligence with a nomination this important.” Senate Judiciary Committee Chairman Charles Grassley, R-Iowa, told the committee, “I would advocate for the position [Flake] took, but I don't control that.”

Earlier Friday, sexual assault survivors confronted Flake in the halls of the Capitol, and a video of the confrontation went viral:

The party-line committee vote came after nearly two hours of debate in which both sides revealed the raw emotions ignited by the extraordinary Thursday hearing on Ford's accusation.

During the Thursday hearing, Ford, frightened but firm, told her story of an alleged sexual assault by Kavanaugh—and his “uproarious laughter”—when they were in high school. Kavanaugh, defiantly and adamantly, denied that assault or any assault ever happened. He called the claims part of a coordinated, and political, attack on his integrity.

Before the vote, female members of the U.S. House lined the back of the Senate judiciary Committee room, and then walked out when the committee refused to delay action in order to call other witnesses. The scene was reminiscent of 1991 when female House members marched from the House side of the Capitol to the Senate to demand serious consideration of Anita Hill's sexual harassment allegations against then-nominee Clarence Thomas.

The Judiciary committee debate began after Republican members voted down a motion by Democratic Sen. Richard Blumenthal of Connecticut to issue a committee subpoena to Kavanaugh's high school friend Mark Judge, who is represented by Cozen O'Connor's Barbara “Biz” Van Gelder.

Van Gelder said in a statement Friday: “If the FBI or any law enforcement agency requests Mr. Judge's cooperation, he will answer any and all questions posed to him.”

Ford alleged that Judge was in the room, decades ago, when Kavanaugh pushed her onto a bed, tore at her clothes and put his hand over her mouth to prevent her screams. Judge, in a letter to the committee, has said he has no recollection of the alleged assault and it is inconsistent with what he knows of Kavanaugh. Ford is represented pro bono by Debra Katz of Katz Marshall & Banks, and Michael Bromwich.

Christine Blasey Ford, center, arrives with her lawyer, Michael Bromwich, left, to testify Thursday. Photographer: Andrew Harnik/Pool via Bloomberg

Grassley said he found Ford, a research psychologist at Stanford and Palo Alto universities, “credible” and “sincere.” But, he said, at the end of the day, the three witnesses (alleged to be at the party where the assault occurred) denied any knowledge of the event she described.

“A person had an allegation made against him in a public way,” Grassley said. “It was only fair that his accuser had the burden of proof and in my opinion, this wasn't met.”

Katz, the lawyer for Ford, said in a statement Friday: “A thorough FBI investigation is critical to developing all the relevant facts. Dr. Christine Blasey Ford welcomes this step in the process, and appreciates the efforts of Senators Flake, Murkowski, Manchin and Collins—and all other senators who have supported an FBI investigation—to ensure it is completed before the Senate votes on Judge Kavanaugh's nomination. No artificial limits as to time or scope should be imposed on this investigation.”

Democratic Sen. Patrick Leahy of Vermont said there were reasons, other than the alleged assault, to question Kavanaugh's credibility. He charged that Kavanaugh had misled the Senate “time and time again” about his knowledge and receipt of stolen Democratic emails when he worked in the George W. Bush White House, as well as his involvement in that administration's controversial policies and judicial nominations.

Kavanaugh's testimony Thursday, in particular, disturbed Leahy, who said Kavanaugh engaged in “angry, baseless, political tirades—conspiratorial madness.” Leahy added, “I've never seen such volatility, partisanship and lack of judicial temperament from any nominee for any court from any administration.”

In his testimony, Kavanaugh, alternately tearful and scornful, accused Democrats of a “search and destroy” mission and revenge for the results of the 2016 presidential election. He appeared before the committee just two days after an unprecedented appearance for a high court nominee on Fox television, with his wife, to plead for a “fair process” in which to make his case.

Ford's testimony over nearly four hours riveted the country as she gave details of the alleged assault. When asked what was her strongest memory, she said laughter by Kavanaugh and Judge. Ford was one of three women who came forward in the last two weeks with sexual misconduct allegations involving Kavanaugh. The committee did not call the other women to testify.

Kavanaugh's nomination in July immediately triggered a high-stakes battle. He is viewed as more conservative than the justice he would succeed, Anthony Kennedy. Kennedy had been the decisive fifth vote on many issues that deeply divide the court and the nation, such as abortion, affirmative action, and gay rights.

Organizations supporting and opposing Kavanaugh have poured millions of dollars into television and other ads in an effort to persuade senators and voters.

But the nomination also has been complicated by deep partisan distrust. During the hearings this week, committee Republicans resurrected the 1987 defeat of Reagan high court nominee Robert Bork by the Democratic-controlled Senate; committee Democrats still seethe over the Republican majority's refusal even to give Obama nominee Merrick Garland a hearing.

Republican Sen. Lindsey Graham of South Carolina told the committee on Friday that if he becomes committee chairman next year, “I'm going to remember this. There's process before Kavanaugh and process after Kavanaugh.”

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Ellis Kim contributed reporting from Washington.