Senate Judiciary Committee Chairman Chuck Grassley on Wednesday unloaded a torrent of criticism on Sen. Dianne Feinstein for her handling of the sexual assault accusations against Supreme Court nominee Brett Kavanaugh, telling the ranking Democrat on the committee, "I cannot overstate how disappointed I am."

Saying Feinstein "chose to sit on the allegations until a politically opportune moment," Grassley demanded she immediately turn over an unredacted copy of the letter from Kavanaugh's accuser, Christine Blasey Ford, that Feinstein received July 30.

Feinstein, D-Calif., shared the letter with federal authorities and other senators only last week, days before a key Judiciary Committee vote on Kavanaugh's confirmation, after a leak about the letter was published in The Intercept. Republicans have accused Democrats of orchestrating that leak.

Grassley, R-Iowa, who called the document a "significant piece of evidence in Judge Kavanaugh's confirmation process," said that despite multiple requests, he still has access only to a redacted copy of the letter included in supplemental background materials provided by the FBI to a select group of senators.

SUPPOSED WITNESS IMPLICATES KAVANAUGH WITHOUT FIRST-HAND KNOWLEDGE -- THEN DELETES POST AFTER QUESTIONS SURFACE

He asserted that he needs the full version of the document in order to "prepare for Monday's hearings" into the allegations against Kavanaugh. Ford's lawyers strongly suggested in a letter late Tuesday that she won't appear at the hearing until the FBI conducts a "full investigation" into her claims.

In a follow-up letter Wednesday, the lawyers, Lisa Banks and Debra Katz, doubled down on that request, even as Republicans characterized it as a stall tactic that did not excuse Ford from providing sworn testimony before the Senate.

"Dr. Ford was reluctantly thrust into the public spotlight only two days ago. She is currently unable to go home, and is receiving ongoing threats to her and her family's safety," the lawyers wrote. "Fairness and respect for her situation dictate that she should have time to deal with this. She continues to believe that a full non-partisan investigation of this matter is needed and she is willing to cooperate with the Committee. "

Just days ago, on Monday, Katz had said her client was willing to testify, telling CBS News, "My client will do whatever is necessary to make sure that the Senate Judiciary Committee has the full story and the full set of allegations to allow them to make a fully informed decision."

And Banks said in an interview, "She will agree to participate in any proceedings that she’s asked to participate in.”

But on Wednesday, the lawyers suggested that more witnesses should be called in order for any hearing to have legitimacy. Earlier in the day, a former classmate of Kavanaugh's said that he had no "recollection" of any incident at the house party Ford described, while another witness who had backed up Ford deleted her account online after inconsistencies surfaced and she admitted her statements were not based on any first-hand knowledge.

"The Committee's stated plan to move forward with a hearing that has only two witnesses is not a fair or good faith investigation; there are multiple witnesses whose names have appeared publicly and should be included in any proceeding," Ford's attorneys wrote. "The rush to a hearing is unnecessary, and contrary to the Committee discovering the truth."

POLYGRAPH TAKEN BY KAVANAUGH ACCUSER COMES UNDER SCRUTINY -- HOW DOES THE TEST WORK?

Sources told Fox News that Senate Republicans aren't the only ones working to get ready for Monday's factfinding hearing, which appears ready to proceed even without Ford's participation. The White House confirmation team on Tuesday conducted a so-called "murder board" with Kavanaugh, to test him with tough questions he might face during his testimony. Kavanaugh did well in the session, the sources said, adding that "he was solid - there was no wavering."

"I cannot overstate how disappointed I am." — Judiciary Committee Chairman Chuck Grassley

However, GOP leaders have signaled there will be no hearing if Ford refuses to show. “If she’s not attending I don’t know what the point of going forward would be,” said Senate Majority Whip John Cornyn, R-Texas, a member of the Judiciary Committee. Republican senators gave Ford a deadline of Friday to indicate whether she will testify next week.

Feinstein appeared to wash her hands of the process in a brief interview outside her Senate office with Fox News on Tuesday, saying, "I have no say, I'm the lead Democrat. ... I think it's really too bad that no one called her, or called her lawyer."

WATCH: FEINSTEIN ADMITS SHE CAN'T GUARANTEE ACCUSER BEING ENTIRELY 'TRUTHFUL'

She added: "This is a woman who has been profoundly impacted by this. Now, I can't say everything's truthful. I don't know."

Top Republicans have said they repeatedly called and emailed Ford's lawyers, and have offered to fly staffers to California "or anywhere else" to speak with Ford. They have also offered her either a public or private hearing, but haven't heard back.

In his letter Wednesday, Grassley unequivocally dismissed Feinstein's suggestions that her delays were motivated by a desire to protect Ford's identity, and suggested that her actions had in fact compromised any legitimate desire to preserve her anonymity.

"These allegations could have been raised to me, or to Judge Kavanaugh, while protecting Dr. Ford's anonymity," Grassley said. "Had Dr. Ford not made her allegations public via The Washington Post over the weekend, I still would not know her identity."

He continued: "These allegations could have been raised both within the last seven weeks and in a way that protected Dr. Ford's anonymity. Instead, you chose to sit on the allegations until a politically opportune moment. I cannot overstate how disappointed I am in this decision."

President Trump echoed that line of argument Wednesday, even as he encouraged Ford to speak to the Judiciary Committee and said she deserved to be heard.

"Why did [Democrats] wait until everything was finished and then bring it up? That doesn't look good," Trump said.

Also on Wednesday, Grassley sent two other letters -- one to Ford's attorneys urging her to appear at Monday's scheduled hearing into her allegations, and another scathing missive to Senate Judiciary Committee Democrats.

READ GRASSLEY'S OVERTURE TO FORD'S LAWYERS, SCATHING LETTERS TO DEMS

In those letters, Grassley railed against Democrats' "abuse of this confirmation process" through "delay and obstruction ... with every argument available." He reiterated that Monday's hearing would remain on the calendar despite Democrats' objections."

"I will view any additional complaints about this process very skeptically," he said.

The Judiciary Committee chairman flatly disputed claims by Ford's lawyers that he had requested Kavanaugh sit at the same "table" with Ford during Monday's hearing, or that he had only sought a publicly televised hearing. Instead, Grassley said, Ford was offered the chance to testify privately in a confidential session with Republican senators and staffers, without Kavanaugh nearby.

Grassley has also repeatedly rejected suggestions by top Democrats and Ford's lawyers that an FBI probe would be appropriate. He specifically dismissed comparisons made by Ford's attorneys to the FBI investigation of Anita Hill's sexual harassment allegations against then-nominee Clarence Thomas in 1991, saying that Hill's allegations were non-public when the FBI conducted a few days of background interviews to assess their validity before forwarding them on to the White House.

Once Hill's allegations became public, Grassley wrote, the Judiciary Committee did not request additional FBI assistance.

"We are in the same position the Committee was in after Professor Hill's allegations were leaked," Grassley said. "After that leak, we did not ask the FBI to conduct an investigation. Instead, we reopened the hearing and assessed the testimony that was given on our own."

For her part, Hill told PBS' "NewsHour" Wednesday that the Judiciary Committee could not be trusted to probe the accusations against Kavanaugh fairly, "because I doubt they are qualified to carry out an investigation in a neutral fashion."

On Tuesday, a federal law enforcement official told Fox News, "It's totally inappropriate for someone to demand we use law enforcement resources to investigate a 35-year-old allegation when she won't go under oath and can't remember key details including when or where it happened."

Fox News has learned from a source close to Sen. Susan Collins, a moderate considered a potential key swing vote in Kavanaugh's confirmation, that she had called the FBI's Deputy Director David Bowdich on Wednesday to learn more about the FBI's potential role in the proceedings as part of her "due diligence."

Meanwhile, Missouri Democratic Sen. Claire McCaskill tweeted Wednesday night that she would not vote for Kavanaugh. In her message, she explicitly wrote that his legal rulings and ideology, and not the allegations by Ford, were the reason for her decision. McCaskill is locked in a tight re-election race in a red state that Trump won handily in 2016.

Fox News' Jake Gibson and John Roberts contributed to this report.