The top Democrat on the Judiciary Committee told reporters Tuesday she can't say if everything Christine Blasey Ford has said is truthful - but said she does believe Judge Brett Kavanaugh's accuser is credible.
Grassley said the committee offered Ford "the opportunity to share her story" in a public or private setting, "whichever makes her most comfortable".
Trump made his remarks a day after lawyers for Christine Blasey Ford, a university professor in California, said she would testify before the Senate Judiciary Committee only if the FBI first investigates her allegation that Kavanaugh sexually assaulted her in 1982 when both were high school students in Maryland. Kavanaugh has called Ford's allegation "completely false". Both Kavanaugh and Ford were called to testify before the committee on Monday, but Ford says she wants an FBI investigation first.
Republicans have been careful to say that Ford should have her chance to speak, and they have stressed that they are willing to move Monday's hearing behind closed doors, if she prefers.
Kavanaugh has agreed to appear on Monday to give his side of the story to the committee.
Lawyers for Christine Blasey Ford say that before she testifies on Capitol Hill next week she wants the FBI to investigate her allegation that she was sexually assaulted by Supreme Court nominee Brett Kavanaugh.
Moderate GOP Sen. Susan Collins of ME, who's had her share of clashes with Trump, said she hoped Ford would reconsider a decision not to testify and "it's not fair to Judge Kavanaugh" if she refuses.
Later on Wednesday, Grassley wrote to the senior Democrat on the committee, Dianne Feinstein, requesting she immediately provide an unredacted copy of the letter Ford sent her in July about the assault allegation, saying he must review it before Monday's hearing. Republicans have said the Federal Bureau of Investigation would be doing nothing more than what committee staffers could achieve by interviewing Kavanaugh and Ford.
"The rush to a hearing is unnecessary, and contrary to the Committee discovering the truth", Banks wrote.
If support for his nomination remains this weak, Trump's pick would rank among the lowest-supported Supreme Court nominees to later be confirmed, according to historical data from Gallup.
"If she shows up, that would be wonderful".
"Not after the sexual charges", said Jeffrey Schmidt, 56, from Colorado, who opposes President Trump and his policies.
Ford alleges that at a house party in the 1980s, a drunken Kavanaugh tried undressing her on a bed and stifling her cries before she fled an accusation Kavanaugh has repeatedly denied. Grassley said he was disturbed to learn of the threats. That could delay the hearing by weeks or months - perhaps even past the mid-term elections in November.
It could do so, on its own or at the behest of the Senate Judiciary Committee.
The back-and-forth came hours after President Trump described the allegation against Kavanaugh as hard to believe and the furor surrounding it as "very unfair" to the judge. But Trump said, "it's really up to the Senate" to decide how to proceed with the confirmation process.
Democrats have said the White House can order a more detailed FBI investigation, as occurred during the 1991 confirmation process for Supreme Court Justice Clarence Thomas after he was accused of sexual harassment. In an interview with The Associated Press, he said the allegation against Kavanaugh, if true, is "close to being disqualifying, if not disqualifying".
"Meanwhile Republicans are trying to bully her into a rigged hearing before a neutral investigation and without the only identified eyewitness", No. 2 Senate Democratic leader Dick Durbin of IL tweeted.
McCaskill's opponent in the midterm election, Republican Attorney General Josh Hawley, said earlier Wednesday on a national conservative talk show that the allegations look to be "an ambush" by Democrats.
Judge's lawyer said in a letter to the committee on Tuesday that Judge did not recall the incident and did not wish to testify.