Kavanaugh's nomination had appeared back on track earlier Friday when he cleared a key hurdle at the Senate Judiciary Committee. But that advance came with an asterisk. Flake indicated he would take the next steps — leading to full Senate approval — only after the further background probe, and there were suggestions that other moderate Republicans might join his revolt.

The abrupt developments gave senators, the White House and millions of Americans following the drama at home hardly a chance to catch their breath after Thursday's emotional Senate hearing featuring Kavanaugh angrily defending himself and accuser Christine Blasey Ford determinedly insisting he assaulted her when they were teens.

Emotions were still running high Friday, and protesters confronted senators in the halls.

"The country is being ripped apart here," said Flake.

After he took his stance, Republican leaders had little choice but to slow their rush to confirm Kavanaugh, whom they had hoped to have in place shortly after the new court term begins Monday.

Trump quietly followed suit, though he had vigorously resisted asking the FBI to probe the allegations of sexual misconduct by Kavanaugh, now being raised by three women. One day earlier, he had blistered the Senate process as "a total sham," accused Democrats of a conspiracy of obstruction and declared on Twitter, "The Senate must vote!"