× Expand (Melina Mara/The Washington Post via AP, Pool)

Since, as I write this, three swing-vote senators on the Brett Kavanaugh nomination—Arizona's Jeff Flake, Alaska's Lisa Murkowski, and West Virginia's Joe Manchin—have all called for an FBI investigation of the allegations against the Supreme Court nominee, I'm guessing the investigation will go forward. Absent such an investigation, it's by no means clear the Republicans have the votes to confirm.

That said, what will the scope of the investigation be? Will it concern only Dr. Christine Blasey Ford's charges in the narrowest sense, and therefore come back saying there's no third-party confirmation for them? Will it talk to the other people in the house where the attempted rape happened that night? Will it go into such contextual matters as whether Kavanaugh was a heavy drinker, and abusive and out of control when drunk?

Whether it goes into such contextual matters is hugely important—because in his testimony Thursday, Kavanaugh asserted under oath that he wasn't a heavy, abusive, out-of-control drinker. If the FBI reports that he was, then he lied to the committee. If the FBI is instructed not to seek such information and not to include it in its report, however, then the odds of his being confirmed would likely rise. If all the bureau comes back with is a report stating that Ford's testimony as to what went on in the bedroom can't be confirmed, the likelihood is that the swing voters—Maine's Susan Collins, as well as Murkoswki, Flake, and Manchin—will likely take that as a clean bill of health and vote to confirm.

Assume, because they otherwise lack the votes to confirm, that Senate Majority Leader Mitch McConnell and then President Trump agree to a one-week FBI investigation. Presumably, however, McConnell and Trump could limit the scope of that investigation. The only way the FBI could perform a more extensive background check would be if those swing Senate voters insisted on it. I can only hope that they do.