Nowhere, that’s where — and now members of both parties want to know why. We have already heard Senate Republicans such as Rand Paul and John Cornyn point to the refusal of Chief Justice John Roberts as a signal that he thinks the process is unconstitutional. Now Democrats in the upper chamber have begun asking why Roberts won’t preside over the trial, the New York Post noted last night:

Chief Justice John Roberts’ refusal to preside over former President Donald Trump’s second impeachment trial is raising questions about whether he views the first-of-its-kind proceedings as constitutional. …

Speaking to MSNBC’s “The Rachel Maddow Show” on Monday evening, Senate Majority Leader Chuck Schumer (D-NY) revealed that Roberts “did not want” to take part in the trial.

“The Constitution says the chief justice presides for a sitting president,” the top-ranking senator said. “So it was up to John Roberts whether he wanted to preside with a president who is no longer sitting, Trump, and he doesn’t want to do it.”

Well, that much is obvious. The question is why Roberts has demurred from presiding. Both Elizabeth Warren and Richard Blumenthal are suggesting that Roberts is shirking, even if he’s not explicitly required to preside:

Even Sen. Elizabeth Warren (D-Mass.) voiced objection to Roberts sitting out the trial last week amid concerns that he would do so.

“That is his constitutional duty. I can’t imagine why a Supreme Court justice would not do his duty,” the liberal pol said.

Sen. Richard Blumenthal (D-Conn.), who serves on the Senate Judiciary Committee, which plays a critical role in the impeachment process, also hoped Roberts would attend.

“I think he should because it will be a straightforward, simple trial. I would think that the chief justice lends the dignity and seriousness it requires,” he said, noting that he was “not required by law to do it.”

Gee, why wouldn’t Roberts volunteer for this duty? Maybe it’s because Warren used the last one to grandstand at Roberts’ expense. Remember this episode?

This is a bizarre question. It's hard to believe it's asked in good faith. She knows that Justice Roberts doesn't have trial judge-type powers over impeachment. Otherwise he could entertain a motion to dismiss the whole case. This is the senate's proceeding, not his. https://t.co/DSkVk1N2hE

— David French (@DavidAFrench) January 30, 2020

Democrats didn’t treat the last impeachment trial with “the dignity and seriousness it requires,” especially in regard to Roberts, whose role is mainly ceremonial anyway. Why would Roberts volunteer to become Warren’s piñata all over again? Or anyone else’s? Roberts got an up-close look at the Senate Democrats’ idea of “dignity and seriousness” a year ago, and doesn’t need another.

That’s why tea-leaves reading over constitutionality probably isn’t worth much in sussing out any signals from Roberts. The Constitution only requires him to preside over the trial of a sitting president; otherwise, that duty falls to the president pro tempore of the Senate or the Vice President. If the Senate wants to hold a trial for someone no longer in office, Roberts has better things to do with his life than assist Warren in self-promotion, and that’s likely the only signal Roberts intends to send.