Republicans, who are trying to retain control of the U.S. Congress in November elections, are seeking to balance their desire to have a conservative judge on the Supreme Court with sensitivity in how they handle the sexual misconduct allegations amid the reverberations of the #MeToo movement.
Ramirez, who says Kavanaugh exposed his genitals to her while they were at Yale, is among four witnesses expected to be interviewed by the FBI in the investigation, commissioned by Trump after an intervention from Arizona Republican senator Jeff Flake, that is set to last less than a week.
"I had planned to just talk to him nicely, but once when I saw that he was voting for Kavanaugh my niceties went out the window", Archila, co-executive director of the non-profit Center for Popular Democracy Action, said in an interview with the Associated Press.
The move suggests that the FBI's background investigation will look beyond separate allegations of attempted rape levelled against Mr Kavanaugh by Dr Christine Blasey Ford at a dramatic Senate hearing on Thursday.
Trump ordered the FBI on Friday to reopen Kavanaugh's background investigation after several women accused Kavanaugh of sexual misconduct.
While the FBI is investigating Ford and Ramirez's allegations, the full parameters of its probe remain unclear.
Amid the new probe, Trump has maintained his support for Kavanaugh, saying that "hopefully at the conclusion, everything will be fine". Following the agreement for the FBI to investigate Kavanaugh, the focus has moved to how the probe will be handled, its ultimate findings and whether it will put to rest fears about a lack of due diligence over the nominee for the nation's highest court. As a result, a full Senate vote on Kavanaugh's confirmation has been delayed for up to a week.
At the White House, President Donald Trump said that though he found Ford's testimony "compelling" and "credible", he was pleased with what Kavanaugh said at the hearing. If all Democrats vote against Kavanaugh, two Republicans would also have to do the same to block his confirmation.
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The U.S. has also accused Iran of promoting global terrorism, which Tehran vehemently denies. Iran has said it is a victim of terrorism rather than a perpetrator.
"F.B.I. agents are experts at interviewing people and quickly dispatching leads to their colleagues around the world to follow with additional interviews", he wrote.
The probe, though, will be limited in scope in ways determined by the White House, a person familiar with the proceedings said on Saturday. Judge has also denied misconduct allegations.
Judge Kavanaugh angrily denied that he had ever assaulted her or anyone else.
Swetnick has claimed, in a sworn statement, that Kavanaugh and Judge engaged in lewd behavior with young women at high school parties, and alleged the two placed drugs or alcohol in punch in order to inebriate women so they could be "gang raped" by other partygoers.
Federal Bureau of Investigation agents are also expected to interview several people whom Ford said were present at the party where the alleged assault took place, including Mark Judge, Patrick J. Smyth and Leland Keyser, sources familiar with the matter told CNN.
"We heard her provide details in that story that can be corroborated and other facts that can be uncovered if we hear from other witnesses", Blumenthal said.
Kavanaugh has called Swetnick's accusations a "joke". Kavanaugh has denied being the perpetrator.
Mr Kavanaugh would not answer directly when he was asked on Thursday if he would agree to an FBI investigation, but said he would do whatever the Judiciary Committee wanted.