Senate Minority Leader Chuck Schumer, D-N.Y., and Judiciary Committee ranking member Dianne Feinstein, D-Calif., wrote a letter to President Trump urging him to direct the FBI to investigate sexual assault allegations against Supreme Court nominee Brett Kavanaugh.

The letter was made public on Sunday moments after the Judiciary Committee announced that Kavanaugh's accuser, Dr. Christine Blasey Ford, would testify about her claim on Thursday.

"The FBI’s involvement is required in order to identify and interview all witnesses, review documentary evidence, and provide its report to the Senate," Schumer and Feinstein wrote. "It is not the FBI’s job to determine credibility, but it is the FBI’s job to gather facts. Regrettably, however, the FBI has thus far failed to act."

The pair of Democrats accused Trump of making "misleading statements" about whether the FBI should investigate Ford's claims against Kavanaugh. They also compared the current controversy to the sexual harassment allegations against Clarence Thomas by Anita Hill in 1991. In that case, the FBI investigated Hill's allegations and produced a report three days later, before the Judiciary Committee held its now-infamous hearings with Hill and Thomas.

"[T]he FBI has almost a full week to do its work," Schumer and Feinstein wrote. " ... [T]here is no legitimate basis for you to continue blocking the FBI from investigating this important matter."

Ford, now a 51-year-old California college professor, went public last week with her allegation that Kavanaugh assaulted her at a party when they were in high school. Kavanaugh, 53, an appellate court judge, denied the allegation and said he wanted to testify as soon as possible to clear his name.

The question of whether Ford would testify before the committee had gone unanswered for several days amid protracted back-and-forth tussling between Senate Republicans and Ford's legal team, who disagreed on the ideal timing of the hearing, as well as who should testify first and whether outside lawyers should be allowed to ask questions.

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Earlier Sunday, Sen. Lindsey Graham, R-S.C., told "Fox News Sunday" that Ford's lawyers were still contesting two GOP conditions — that Ford and Kavanaugh would be the only witnesses and that an independent counsel would ask the questions.

Graham promised a fair hearing in which both Ford and Kavanaugh "will be challenged" but added that "unless there's something more" to back up her accusation, then he's "not going to ruin Judge Kavanaugh's life over this."

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"I want to listen to her, but I'm being honest with you and everybody else. ...What am I supposed to do?" Graham asked, explaining his dilemma over an allegation of a 1980s incident that is past the statute of limitations for criminal charges. "But she should come forward. She should have her say."

Fox News' Chris Wallace and The Associated Press contributed to this report.