And then there are the other witnesses, the John Boltons and Rudy Giulianis—witnesses who will not come willingly but could be, with court intervention, persuaded or compelled to come. This group of witnesses represents the major wild card. Democrats may be forced to go ahead without them, depending on how tenacious these witnesses are in tying things up in litigation. But they also could prove most damaging to the president if they end up testifying.

With procedures now settled for the ongoing impeachment inquiry, The Washington Post reports that House Democrats are planning on a series of “blockbuster” public hearings with witnesses such as Taylor, Vindman, and Ambassador Marie Yovanovitch, who was ousted from her post in Ukraine at Trump’s request. To some extent, Republicans are putting on a brave face: The Post quotes Representative Peter King insisting, “I think people will see there’s very little there.”

But the prospect of the House conducting such hearings in public, with credible witnesses who are all telling variants of the same damning story as seen from their own angle, creates problems for the president’s defenders. How do you complain about secrecy when the proceedings are no longer behind closed doors? How do you attack the integrity of witnesses against whom your previous attempted attacks have already failed, when they are on television seeming like credible public servants trying to do their jobs? How do you defend presidential conduct, when the president’s own staff is describing it in alarming terms?

So far, the president’s defense—for all its triviality—has worked pretty well in maintaining his core support. While support for impeachment has grown significantly, the president’s approval rating has held up reasonably robustly, dropping only half a percentage point in the FiveThirtyEight average from October 1 to November 1. There is little prospect of congressional Republicans abandoning the president as long as this resilience in his job-approval numbers persists. So the key question is whether support for the president among Republican voters will meaningfully erode in the face of a more public presentation of the president’s behavior with respect to Ukraine.

That may depend on which theme predominates in the president’s defense in this new phase. Trump, at least, seems to favor his traditional approach: shooting the messengers. He has tweeted incessantly demanding to know more about the whistle-blower whose complaint pushed the Ukraine scandal into the public eye, and suggested to reporters on November 3 that they would be “doing the public a service” by revealing the person’s identity. The president has never been much constrained by reality, but it’s hard to see how fruitful this tactic is likely to be, given that the whistle-blower’s account of Trump’s actions toward Ukraine has now been corroborated by witnesses such as Taylor, Hill, and Vindman. Continuing to focus on the whistle-blower while firsthand participants in the story are testifying about what happened is a bit of a non sequitur.