Presumably they were holding back just in case events intervened somehow to disrupt the impeachment process. Maybe Pelosi wouldn’t follow through. Or maybe Republicans would lose interest in calling Hunter Biden as a witness, for whatever reason. No sense in opening this can of worms and inadvertently helping Trump alert the public to possible shenanigans in the Obama administration’s Ukraine policy until they absolutely had to.

Well, today’s the opening day of the trial and GOPers are vowing to call Hunter if Democrats get any witnesses, which seems likely. Team Biden is now at the “absolutely have to” stage. The battle over Burisma will soon be joined. They have no choice but to engage.

House Democrats have already staked out their terrain in that battle: Relevance. Adam Schiff pressed the case this morning in an interview with CBS.

“It would certainly be fair for the president and his team to be able to call witnesses that can provide material information on the charges. It would not be appropriate for the president to seek to call witnesses merely to try to perpetuate the same smear campaign that was foiled when his plot was discovered,” Schiff told O’Donnell. “Hunter Biden, for example, can’t tell us anything about whether the president withheld military aid, whether he withheld that aid to coerce Ukraine to conduct political investigations. Or why he wouldn’t meet with the president of Ukraine.”

That’s a key point made by various Dems. It’s not just that Hunter Biden is arguably irrelevant, it’s that putting him on the stand and using the trial to cast aspersions about Joe’s ethics was allegedly the whole point of the Ukraine pressure campaign to begin with. Ironically, by impeaching Trump for it, Democrats would have handed him a national stage on which to impugn Biden instead of doing it via press releases by the Ukrainian government. Law prof Joshua Geltzer is so worried about it that he’s urging Dems in an op-ed today to consider dropping their demands for witnesses, knowing that testimony from Hunter would be the price for testimony from John Bolton.

But if a Biden is a witness, his actual testimony would not matter because Mr. Trump, loudly echoed by his political and media allies, would endlessly insist that the Biden family’s impropriety had been proven beyond any doubt by needing to testify before the Senate about its purported misdeeds. Fox News would roll endless clips of the questions Senate Republicans would ask of either Biden while keeping the cameras on the witness, then cutting away before showing the answers. This would be enough — more than enough — to lead many Americans to believe that Joe Biden indeed had done something wrong, even if they couldn’t say exactly what it was…

Whatever they think of Mr. Trump’s conduct, Senate Republicans should not push for the corruption of our democracy that even a foreign government refused to provide. And Democrats should resist any such push — thinking very hard, in particular, before trading Mr. Biden’s testimony for, say, the testimony of Mr. Bolton or Mr. Mulvaney. There’s no equivalence between a relevant witness and an irrelevant one. And it would be a high price to pay to fulfill Mr. Trump’s very goal that got him impeached in the first place.

That’s a hard strategic question for Democrats, I think. They don’t know how juicy Bolton’s testimony will actually be. My guess is it would be roughly as damning as Gordon Sondland’s, with Bolton conceding that he believed there was a quid pro quo with Ukraine involving military aid for Biden probes but lacking any sort of private confirmation from Trump, especially that his motive for getting Biden dirt was electoral rather than exposing public corruption. It’ll be easy for Senate Republicans to ignore that. (“There’s no confession!”) And since the outcome of the trial is assured either way, in the end Democrats would gain nothing meaningful from Bolton’s testimony.

But they might lose something meaningful in terms of their frontrunner’s electability if Geltzer’s prophesy of how Hunter’s testimony will be spun comes true.

Maybe in the end they’ll seize the opportunity presented by Trump’s own defense lawyers, who reportedly want Bolton to testify in secret if he testifies at all. Fine, Democrats might say, but then Hunter testifies secretly as well. Closed-door depositions for both. Then they can leak what they want from Bolton’s testimony and hope that the GOP leaks from Biden’s testimony aren’t too damaging.

But they shouldn’t kid themselves. No matter what happens with Hunter in the next few weeks, the Biden family’s lucrative connections by dint of Joe’s fame and influence will be litigated during the campaign. Spend some time with this Peter Schweizer piece from this past weekend as preparation.

As for the video, it’s not the format I expected. I thought it’d be graphics-heavy, with a narrator talking over archival footage. Instead you’re forced to have a virtual beer with the head of Biden’s rapid response team. That’s weird, but I assume that format tested well with focus groups. The idea, presumably, is that you’re more likely to believe a guy chatting at you in a “friendly” setting than you are some nameless, faceless voiceover.