Christine Blasey Ford and Brett M. Kavanaugh. (Melina Mara (left); Matt McClain (right)/The Washington Post)

Chris Coons, a Democrat, represents Delaware in the U.S. Senate and is a member of the Senate Judiciary Committee.

Over recent weeks, as the Senate and our nation have wrestled with the serious allegations of sexual assault made against Judge Brett M. Kavanaugh, I’ve been reminded of the famous words from Sen. Daniel Patrick Moynihan: “Everyone is entitled to their own opinion, but not to their own facts.”

Last week, the country witnessed a difficult, emotional hearing in the Senate Judiciary Committee during which both Christine Blasey Ford, a psychology professor at Palo Alto University, and Kavanaugh, the Supreme Court nominee, testified that they were each 100 percent certain of the facts they presented regarding an alleged sexual assault more than 30 years ago — facts that cannot easily be reconciled.

As a result, senators on the committee were divided not only by our passionately clashing opinions but also by different sets of facts altogether that have torn the committee apart. That’s why Sen. Jeff Flake (R-Ariz.) and I worked to strike a compromise to delay the Senate’s final vote on Kavanaugh’s confirmation by one week to allow the FBI to investigate all credible current allegations before the committee and, hopefully, to give senators one set of facts to work from.

Make no mistake: The FBI is up to the task of making real progress in investigating these thorny allegations within a week. But it can do so only if FBI agents are given the resources and authority to pursue parallel investigations and to follow up on leads promptly so that they can, as President Trump recently said, “interview whoever they deem appropriate, at their discretion” and take all logical investigatory steps in pursuing the allegations before the committee.

After reading initial news reports about the narrow scope of the investigation, hearing from witnesses and sources who have not yet been able to speak with the FBI, and speaking both with my Senate colleagues and directly with White House counsel Donald McGahn this weekend, I am encouraged in some ways. But in other ways I remain very concerned that we might not get the prompt but thorough investigation that these serious allegations warrant and that the Senate and the American people deserve.

So, let me be clear about what this investigation should include.

First, the White House, which has assured me this investigation will be done “by the book,” should clarify what “by the book” means by stating what its scope is and what procedures are in place for the investigation. Doing so can help build confidence in the credibility of this investigation.

Second, the FBI needs to be able to pursue the facts wherever they lead, and that means interviewing all witnesses who can provide context to the credibility of allegations made by Ford and others as well as Kavanaugh’s denials. To be clear, four or five interviews doesn’t cut it. The investigation should include interviews with Ford and Kavanaugh, as well as others they identify and whomever the FBI finds in the course of its investigation who can corroborate or dispute their accounts. That will give the FBI a more complete, better- contextualized understanding of the facts it is able to gather.

Third, this investigation should also include analysis of documentary evidence that is obviously relevant to these allegations, such as Kavanaugh’s calendar and the employment records of Mark Judge, who Ford claims was in the room during the alleged assault.

If the witnesses and evidence I’ve described above are not within the scope of the FBI supplemental background investigation, I don’t believe it will be credible.

Some of my Republican colleagues have repeatedly pointed to the fact that the FBI does not reach conclusions in these investigations, which is true. The FBI does, however, prepare detailed investigation notes from witness interviews. Those documents, once completed, should be made promptly available to all senators well before a final vote on Kavanaugh takes place.

It has become abundantly clear that the American people have strongly held and strikingly divergent opinions about the allegations against Kavanaugh, and those differences have only worsened the corrosive divisions in our country.

This is a crucial moment for the reputations of our institutions — from the Senate to the FBI to the Supreme Court — to demonstrate that we can properly address allegations of sexual assault in a fair process, and it’s vitally important that this investigation is done properly.

Since Friday, I have been urging the White House and my Senate colleagues to ensure this investigation is conducted in a way that allows members of the Senate and the American people to assess these allegations and Kavanaugh’s nomination from a single set of facts. Everyone — Republicans, Democrats, Ford and Kavanaugh — deserves that.