Hard to understate the amount of unscripted drama in the Senate right now. Everyone thought this thing would be over by lunchtime. Now no one knows anything.

Here's the nuts and bolts of it: Senate needs to pass a new resolution laying out format of the rest of the trial. They can do that the easy way (with R consent) or the hard way (via cloture).

Per multiple sources, they are negotiating right now over what that format would look like. Several key R senators are huddled in Whip @SenJohnThune's office, for instance. Some still think it could all get settled today in some manner.

One thing to keep in mind: when Trump lawyers threaten to call hundreds of witnesses, it's NOT up to them. It's up to the Senate, and the question is where the interests of Rs and Ds align to bring this to a relatively efficient close.

This much is for sure: the vast bulk of senators came in this morning not expecting the managers to call any witnesses, including most Democrats. As as MVDV suggested, the defense team had that expectation as well.