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Senate Republicans rule out an FBI investigation into Brett Kavanaugh.

Iowa Senator Chuck Grassley, who chairs the Senate Judiciary Committee, told Christine Blasey Ford’s lawyers in a letter on Wednesday that it is “not the FBI’s role to investigate a matter such as this.” He also repeated his invitation for her to testify in an open or closed session scheduled for Monday, with an implicit deadline of 10 a.m. on Friday for her to accept or decline.

In a letter sent on Tuesday night, Blasey’s lawyers did not explicitly reject the invitation to Monday’s scheduled hearing, but insisted that the FBI first investigate her claims that the Supreme Court nominee sexually assaulted her in high school in the early 1980s. Senate Democrats have largely backed her request, noting that the bureau questioned witnesses about Anita Hill’s sexual-harassment allegation against Clarence Thomas in 1991. That inquiry took place before the background-check process had ended and before the allegation became public knowledge.

Grassley struck a conciliatory tone while firmly rejecting the substance of Blasey’s request in his reply. “We have no power to commandeer an executive branch agency into conducting our due diligence,” he wrote. “The job of assessing and investigating a nominee’s qualifications in order to decide whether to consent to the nomination is ours and ours alone.” Under FBI rules, President Donald Trump would have to order the bureau to reopen the background-check process.

Kavanaugh has denied any wrongdoing and issued a statement over the weekend affirming his willingness to testify before the committee on the matter. It’s unclear whether Republicans would cancel that opportunity on Monday if Blasey declines to participate. Some GOP senators have indicated that they would vote immediately on his confirmation to the Supreme Court if she does not testify.