Like I said Friday, I think lefties and more centrist Democrats will be of two different minds about this. If you’re a progressive, as Sherrod Brown is, then sure, haul Hunter Biden in there. Who cares? If that’s the price of forcing meaningful prosecution witnesses like John Bolton or Mick Mulvaney to testify, so be it. And if Hunter ends up hurting DINO favorite Joe Biden via his testimony, eh. Maybe that’ll redound to Bernie Sanders’s advantage in the primaries.

Whereas if you’re a centrist Democrat and you think it’s Biden or bust in terms of beating Trump next year, hoo boy. Is risking damage to Joe really worth it when Bolton’s testimony won’t mean a thing to the eventual verdict in this trial?

It’ll be fascinating watching lefties and establishmentarians tussle over this question in the next week or so. Watch Brown, then read on.

Jerry Nadler was asked about Hunter Biden testifying this morning and had an interesting response. John Roberts has the first say, he reminded CBS.

MARGARET BRENNAN: So, you’re saying no way would Hunter Biden ever be called to testify?

REP. NADLER: Well, I’m saying that Hunter Biden has no knowledge of the accusations against the president. Did the president, as we said- as the evidence shows that he did, betray his country by conspiring with a foreign country to- to try to rig the election? Hunter Biden has nothing to say about that. They’re- they’re asking for Hunter Biden is just more of a smear of Hunter Biden that the president’s trying to get the Ukraine to do. But the fact of the matter is, let the chief justice rule on- on–

MARGARET BRENNAN: Well–

REP. NADLER: –the chief justice in the first instance rules on evidence. The Senate can overrule him.

MARGARET BRENNAN: Yeah.

REP. NADLER: But no chief justice would- would- would think of- of admitting evidence that- that is not relevant–

As I understand it, if Trump’s team attempts to call Hunter Biden and House Democrats object on relevance grounds, Roberts could issue a ruling. Then McConnell could ask for a floor vote on whether to uphold Roberts’s ruling. In the end, whatever 51 senators want to do is what’ll be done. But Roberts’s initial ruling could be influential, both in terms of public opinion and among Senate centrists like Susan Collins whose votes will be decisive. If Roberts thinks Biden isn’t relevant, that’s a ready-made attack line for Democrats: The one guy at the trial who really is impartial opposed calling him. And although it’s hard to believe a Collins or Cory Gardner would deny Trump the right to call Biden, if they’re so inclined for whatever reason they could point to Roberts’s opinion as cover. “Who am I to contradict the chief justice on a point of law?”

I’m sure McConnell sees that coming, which is why I wonder if the rules they set for the trial on Tuesday will attempt to limit Roberts’s power to issue those sorts of rulings. “On any point of law, the chief justice shall invite the Senate to vote. If the Senate declines to vote, the chief justice may rule.” Something like that. McConnell doesn’t want Roberts offering his opinion on matters like relevance if he can prevent it.

Speaking of which, CBS asked John Cornyn this morning about another potential blockbuster witness in the case, Rudy Giuliani. Cornyn’s answer made me laugh.

“That’s a relationship that causes some of us to sort of scratch our heads,” the Texas Republican said on CBS’s “Face the Nation.” “But I’d say he’s not relevant to the articles and what the Senate is going to be asked to do, impeaching a president for the third time in American history for a non-crime over events that never occurred.”

There are good reasons not to want Rudy to testify. He’d slow down the trial considerably by asserting attorney-client privilege to all sorts of questions; he’d use the platform provided by the trial to rant and grandstand semi-coherently, turning it into a circus; and he, er, might incriminate the president in all sorts of ways if he did choose to answer questions, creating a political nightmare for Republicans. The one reason not to object to Rudy testifying is … relevance. Apart from Trump himself, as the point man on the pressure campaign towards Ukraine Giuliani is the most relevant witness there is. The fact that Cornyn, a former judge(!), is reaching for “relevance” to excuse him shows you just how desperate Republicans are to find a “neutral” reason to justify not calling him.

By the way, some lefties on political Twitter this morning were revisiting this quote from Trump on December 3. Expect to see it feature in Democratic talking points this week: “It will be fair in the Senate,” he said at the time, adding, “I would love to have Mike Pompeo and Mick and I would love to have Rick Perry, and many other people testify. But I don’t want them to testify when this is a total fix” in the House. The president has since shifted his rationale on why Bolton, Mulvaney, and the rest shouldn’t testify even in the Senate, but he’ll take some heat over it soon. As Brown says in the clip above, the reason House Dems declined to call witnesses like Bolton is because Trump insisted on “absolute immunity,” barring them from even appearing before Schiff’s committee. Now’s the president’s chance to free those witnesses to participate in a “fair” process led by Republicans!

Here’s Chris Wallace taking it to Dem impeachment manager Hakeem Jeffries on the timing here. How can impeachment have been an “urgent” matter for Democrats such that they couldn’t afford to wait to fight Trump in court over Bolton’s and Mulvaney’s testimony … and yet also sufficiently non-urgent that Pelosi could hold the articles of impeachment for the better part of a month?