WASHINGTON (AP) — Chief Justice John Roberts was never going to be vote No. 51.

Roberts said Friday that he had no intention of breaking a tie in President Donald Trump’s Senate impeachment trial, dispelling something of a mystery that had hung over the proceedings.

The statement from Roberts came before senators prepared to vote on a resolution setting the schedule for the final stages of the trial. Senators are expected to vote Wednesday on whether to acquit Trump. Earlier in the evening, they voted by a 51-49 margin to reject witnesses at the trial.

The question of whether a chief justice is empowered to break a tie in an impeachment trial is regarded as an open issue among legal scholars.

Roberts was responding to a question from Senate Minority Leader Chuck Schumer, who asked Roberts if he was aware that in the impeachment trial of Andrew Johnson in 1868, the presiding chief justice cast two tie-breaking votes.

Roberts said he was, explaining that one concerned a motion to adjourn while the other involved a motion to close deliberations.

“I do not regard those isolated episodes 150 years ago as sufficient to support a general authority to break ties,” Roberts said. “I think it would inappropriate for me, an unelected official from a different branch of government, to assert the power to change that result so that the motion would succeed.”

Before the chief justice’s statement, former Clinton Justice Department official and Duke University emeritus law professor Walter Dellinger had called it a close question whether the chief justice could break ties at an impeachment trial. Dellinger argued that he could, but he also predicted correctly that Roberts would decline to do so.

“It seems wise to keep the court as far as possible out of the political fray,” Dellinger said after Roberts’ statement.

And Dellinger said he believes Roberts’ answer to the question of whether the chief justice can or should break ties at an impeachment trial will have a lasting impact.

“I think the issue is now put to rest by Chief Justice Roberts for all future impeachments,” he said, adding, “I think this really does establish the precedent.”

Dellinger noted that Roberts has long been known for his meticulous preparation, ready for any question when he argued as a lawyer before the Supreme Court before becoming a judge and then chief justice. He speculated that Roberts arrived at the impeachment trial equally prepared to answer the question of whether he could break a tie.

“He arrived the first day with that statement in his briefcase, I’m sure,” Dellinger said.