Mitch McConnell is still refusing to describe how the Senate trial on the impeachment of Donald Trump will be structured. However, The New York Times reports that the Republican leader is clear on one point: no witnesses allowed.

In just the few days since Trump was impeached in the House, additional evidence has appeared concerning his monthslong attempt to extort Ukraine into manufacturing dirt for use against one of his potential opponents in the 2020 election, Vice President Joe Biden. That includes emails showing that Trump blocked military assistance to Ukraine just minutes after his phone call with the Ukrainian president; Office of Management and Budget officials admitting that Trump’s action was illegal; and White House attorneys cooking up a theory that it was all just fine because Trump is genuinely above the law. This new information, and the fact that Trump blocked the most critical witnesses from appearing before the House, are really good reasons that there should be witnesses at Trump’s Senate trial.

But according to the Times, McConnell is nixing any possibility of witnesses, and has warned other Republicans that allowing any witnesses to speak would provide “an opening for uncertainty during the trial.”

It’s worth taking a moment to understand what McConnell means by this. If there’s anything that can be said about the trial at the moment, it’s that everything about it is uncertain. There’s no information about its length, about the rules under such it will be conducted, or about any other aspect of it. McConnell has even floated the idea of bringing in some of Trump’s most vocal supporters in the House as kind of special advisers to the Senate, which would be a genuinely unsettling action.

But when McConnell says he’s worried about “an opening for uncertainty,” what he really means is that someone might say something. If they actually had Mick Mulvaney there to confess that the OMB knew that placing a hold on the assistance was illegal, or had Bolton there to talk about the actual harm done by Trump’s actions, or had Rudy Giuliani spilling his guts about smearing an ambassador for the benefit of “his client”—if the Senate heard any of those things, it might have to listen.

Of course, it remains unlikely that enough Republicans would vote for removal to threaten Trump, even if Giuliani showed up to confess actual murder. But any witnesses, and perhaps especially those OMB officials who scrambled to enforce Trump’s 84-day delay, while simultaneously admitting that they knew it was wrong, might be enough not only to peel away some Republicans up for reelection, but also to threaten others on the bubble. Like, say, Mitch McConnell.

McConnell is flat-out saying that he can’t allow witnesses because witnesses might give evidence that Trump can’t withstand. Which is pretty good evidence all on its own.

Published with permission from Daily Kos.