Washington CNN  — 

Chief Justice John Roberts made crystal clear Friday night that he has no intention of intervening in the Senate impeachment trial of President Donald Trump by casting a tie-breaking vote.

Speculation had mounted during the trial whether Roberts would act, as Democrats hoped the chief could help them force the Republican majority to allow witnesses to be called. A chief justice had previously settled Senate ties in an impeachment trial – back in 1868 – Senate Minority Leader Chuck Schumer, a New York Democrat, noted.

But when asked directly about whether he would get involved, Roberts said he would not.

Here’s the exchange:

Schumer: “Is the chief justice aware that in the impeachment trial of President Johnson, Chief Justice Chase, as presiding officer, cast tie-breaking votes on both March 31 and April 2, 1868?”

Roberts: “I am, Mr. Leader. The one concerned a motion to adjourn; the other concerned 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. If the members of this body elected by the people and accountable to them divide equally on a motion, the normal rule is that the motion fails. I think it would be 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.”

Ready for the question

Roberts was prepared for this moment, with a response to Schumer at the ready. The chief had narrowly avoided having to preside over a 50-50 split earlier Friday, when the Senate rejected by 49-51 the Democratic effort to call witnesses to the trial.

On the court, with four liberals and five conservatives, Roberts is essentially the decider for how the justices will rule on controversial issues. The George W. Bush appointee has been at the center of rulings on campaign finance, the Voting Rights Act and, famously, saving Obamacare in 2012.

But despite his longtime prominence, Roberts has been in the public spotlight this month more than ever before. The Supreme Court doesn’t allow cameras or TV coverage of arguments, so while Roberts oversees the federal judiciary, most Americans had likely not seen or heard him doing so.

In public speeches, Roberts routinely declares that judges are not like politicians and that their rulings arise from facts and the law.

“When you live in a politically polarized environment,” he said in a New York appearance last year. “People tend to see everything in those terms.”

The Constitution establishes the chief justice as the presiding officer for an impeachment trial, but it is unspecific about how much power that person would have.

In Johnson’s 1868 trial, Chief Justice Salmon Chase broke tie votes twice, but his overall political approach remains controversial today. In 1999, when Chief Justice William Rehnquist oversaw the impeachment trial of President Bill Clinton, he never faced an evenly split Senate vote. Rehnquist saw his role as more ministerial than the authority Chase had seized.

Roberts, a former Rehnquist clerk, took the latter approach.

Overall, Roberts has firmly enforced Senate impeachment rules.

Early on, he warned the dueling legal teams to watch their inflammatory rhetoric, referring to a 1905 case that condemned the use of the word “pettifogging.” And just as with Friday evening’s declaration, Roberts had appeared to have language at the ready to cite.

On Thursday, Roberts was irked by Sen. Rand Paul’s effort to force him to read the name of the alleged whistleblower who had brought attention to Trump’s July conversation with Ukraine’s President over security aid and a possible Ukrainian investigation into former Vice President Joe Biden.

After Roberts made his declaration Friday night, Democrats proposed an amendment that would give him the authority and responsibility to rule on motions to subpoena witnesses and documents. The Senate, on party lines, sidelined the motion.

This story has been updated with additional details of Roberts’ action.

CNN’s Joan Biskupic and Nicolle Okoren contributed to this report.