With that said if I were Warren, Sanders, Kobachar and Bennet I would vote against new witnesses so that I could get back on campaign trail. I would explain my vote with it's more important to be out campaigning for a change than to be sitting in the Senate chambers with a known outcome of acquittal.
Fox Business just reported that Mitch McConnell has stated that the GOP currently lacks the votes to block witnesses. And on it goes...