WASHINGTON (AP) — America's last prolonged look at Chief Justice John Roberts came 14 years ago, when he told senators during his Supreme Court confirmation hearing that judges should be like baseball umpires, impartially calling balls and strikes.

“Nobody ever went to a ballgame to see the umpire,” Roberts said.

His hair grayer, the 64-year-old Roberts will return to the public eye as he makes the short trip from the Supreme Court to the Senate to preside over President Donald Trump’s impeachment trial. He will be in the national spotlight, but will strive to be like that umpire — doing his best to avoid the partisan mire.

“He's going to look the part, he's going to play the part and he's the last person who wants the part,” said Carter Phillips, who has argued 88 Supreme Court cases, 43 of them in front of Roberts.

He has a ready model he can follow: Chief Justice William Rehnquist, who never became the center of attention when he presided over President Bill Clinton's Senate trial.

As Roberts moves from the camera-free, relative anonymity of the Supreme Court to the glare of television lights in the Senate, he will have the chance to demonstrate by example what he has preached relentlessly in recent years: Judges are not politicians.

He has stuck to his mantra even as he and his fellow, Republican appointees hold a firm 5-4 conservative majority on the Supreme Court. Roberts has a solidly conservative voting record on the court, with a couple of notable exceptions that include sustaining President Barack Obama's health care law.

Trump has been among Roberts' critics, blasting the chief justice for his health care votes. While Roberts ignored those remarks, at least publicly, he clashed with the president last year when Trump lashed out at an “Obama judge" who ruled against the president's migrant asylum policy.

It's not as though there isn't plenty of controversy brewing in his regular place of work. Before the end of June, the justices are expected to decide cases involving guns, abortion, subpoenas for Trump financial records, workplace protections for LGBT people and the fate of an Obama-era program that shields young immigrants from deportation. It's possible the court will be asked to hear yet another case on the health care law before the term ends.

The high court has moved to the right with the addition of two Trump appointees, Justices Neil Gorsuch and Brett Kavanaugh, a development that has made Roberts the justice closest to its ideological center and most able to decide how far the court will move to the right, or left, in any case that otherwise divides liberals and conservatives.

In the Senate, though, the chief justice's powers are limited because any ruling he makes can be overridden by a majority vote.

He is not likely to put himself in the position of inviting reversal, said Paul M.Collins Jr., a political scientist and director of legal studies at the University of Massachusetts, Amherst.

“Any controversial rulings in support of either party will threaten the viewpoint that the court should be above politics. Democrats would perceive any ruling for Republicans as partisan and if he ruled against the president, Republicans would allege he is holding a grudge," Collins said. The Senate's impeachment rules allow Roberts to put questions to a Senate vote, without first ruling himself.

Rehnquist looked back on his role in the Clinton trial with a smile. "I did nothing in particular and I did it very well," Rehnquist recalled two years after the trial, borrowing a line from a Gilbert and Sullivan operetta.

Like Rehnquist, Roberts has virtually no experience running a trial, as opposed to the appellate proceedings at the Supreme Court. “I would be shocked if he suddenly becomes a very rigid jurist with respect to technical evidentiary rules,” Phillips said.

The mechanics of the trial are not yet clear. Rehnquist had his top aide at the court, James Duff, and at least one law clerk on hand. He regularly consulted with the Senate parliamentarian before announcing rulings.

Roberts runs a more flexible Supreme Court than Rehnquist, who would cut off lawyers mid-sentence when the red light came on to show their time was up.

Whenever Roberts appears in public, inside the courtroom or elsewhere, he exudes a calm confidence that comes at least in part from preparation. As a leading Supreme Court advocate earlier in his career, Roberts would practice for high court arguments with his main points on five index cards. He rehearsed so that he could make those points in any order and be ready to answer 1,000 questions, even if he might only face 80 to 100 queries during a typical 30-minute argument, he told author Bryan Garner in an interview early in his tenure as chief justice.

He also has a quick wit that he has used to settle confusing situations. When the lights dimmed and then went out during arguments in 2016, Roberts quipped, “I knew we should have paid that bill."

Soon after he became chief justice, a light bulb exploded in the courtroom, startling the crowd, justices and court police included. Roberts helped restore calm by calling the incident “a trick they play on new chief justices all the time."