Some Democrats are beginning to opine that Roberts could save the Senate from itself and force consideration of witnesses if there’s a tie. As Sen. Jon Tester (D-Mont.) put it: “If he wants a fair, impartial trial and get the evidence out, I think there’s a fair shot he would vote for witnesses.”

It’s a hypothetical that Democratic leaders have privately considered for months, as soon as it became clear the House was going to send impeachment articles over to the Senate, according to Democratic aides. They have sought guidance from the Senate parliamentarian’s office on the issue, although so far, that hasn’t been forthcoming as it hasn’t formally arisen during the Trump trial.

Yet the smart money is still on Roberts staying out of it, or GOP leaders muscling through a 51-49 vote that avoids placing responsibility for the course of the trial on Roberts. Because if the vote is tied, no matter what the chief justice does, it will be hotly debated for years to come.