Washington (CNN) Since the Senate impeachment trial began last week, Chief Justice John Roberts has been mainly out of the camera's line of sight. He has, clerk-like, enforced Senate procedures and kept the clock for the lawyers at the lectern. He has tried to maintain the chamber's decorum, as when he admonished the legal teams against nastiness, citing a 1905 Senate trial precedent against use of the word "pettifogging."

He has introduced some levity, as when Senate Majority Leader Mitch McConnell wished him happy birthday on Monday and the 65-year-old Roberts responded with: "Well, thank you very much for those kind wishes, and thank you to all the senators for not asking for the yeas and nays."

Beginning Wednesday, Roberts will be less lighthearted and far more visible. He will be the voice of senators, with his visage at the center of the screen as he reads their questions. Roberts will pose questions that the senators write on forms to the US House managers and President Donald Trump's lawyers.

If he follows the model of Chief Justice William Rehnquist in the 1999 trial of President Bill Clinton, Roberts will state the questions with as little inflection and emotion as possible, reading verbatim from the forms. At the start of each query, Roberts is expected -- per tradition -- to announce which senator has put forward the question.

Yet it could get awkward, as the chief justice of the United States may be pressed to ask questions -- based on some of the assertions already made in the chamber -- related to Trump as "a cheat ... who got caught" or, alternatively, to Hunter Biden, son of former Vice President Joe Biden, who has been targeted by Trump's defense team.

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