Brett Kavanaugh's confirmation was suddenly thrown into doubt Friday after Republicans and the White House agreed to a one-week delay so the FBI can investigate sexual assault allegations facing President Donald Trump's Supreme Court nominee.

"I've ordered the FBI to conduct a supplemental investigation to update Judge Kavanaugh's file," Trump said in a statement. "As the Senate has requested, this update must be limited in scope and completed in less than one week."

The fast-moving developments Friday mean that the full Senate will not vote early next week, as expected. Members voted Friday night to formally open consideration of Kavanaugh's nomination, a procedural move that allows Senate Majority Leader Mitch McConnell to keep his options open.

The delay is the result of a last-minute change of heart by Arizona Sen. Jeff Flake, whose stunning move to force an investigation was quickly backed by several senators considered swing votes on Kavanaugh's confirmation.

Flake made the demand for the FBI probe after a chaotic scene at a Senate Judiciary Committee meeting in which the panel advanced Kavanaugh by a 11-10 party line vote -- saying his vote was conditioned on a probe taking place, and that he would oppose Kavanaugh on the floor of the Senate unless his demand was met.

Swing votes Alaska GOP Sen. Lisa Murkowski, Maine GOP Sen. Susan Collins and Democratic Sen. Joe Manchin subsequently backed an FBI investigation before they'll vote to confirm Kavanaugh.

The Judiciary Committee officially requested the FBI investigation, saying it should probe "current credible allegations" against Kavanaugh, and Republicans said it would be up to the FBI to decide what allegations are considered credible.

It was Flake, Collins and Murkowski who set the terms of the investigation, three sources familiar with the matter told CNN.

A separate Republican source familiar with the matter told CNN that the undecided GOP senators believe a key FBI focus should be on, but not limited to, Mark Judge, Kavanaugh's friend who Christine Blasey Ford has alleged was also in the room during the alleged assault and is also named as a witness to other incidents alleged by Julie Swetnick. Judge has said he does not recall incidents alleged by Ford or Swetnick. Kavanaugh has denied allegations made by Ford and Swetnick.

Separately, on timing, a senior GOP leadership aide told CNN the agreement among the three key Republican senators and GOP leadership was to take the first key procedural vote on the Senate floor on the nomination no later than next Friday. It could happen earlier if the FBI is finished before then.

The expectation is that like other FBI background checks, the results of the FBI's investigation will be private and put in Kavanaugh's file and made available to senators but not the public, the aide said.

The tumult came just hours after Kavanaugh appeared to be on solid footing, with Republicans rallying to his side after his denials of Christine Blasey Ford's allegation in a Judiciary Committee hearing Thursday.

In a statement Friday, Kavanaugh said he would "continue to cooperate" with the FBI. (CNN)

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