The statement went farther than Ms. Collins had before, and was sure to please Democrats who have been feverishly arguing in favor of live witness testimony at the trial and compelling new evidence. “While I need to hear the case argued and the questions answered, I tend to believe having additional information would be helpful,” she said in a statement. “It is likely that I would support a motion to call witnesses at that point in the trial just as I did in 1999.”

Ms. Collins cautioned she would need to hear arguments from the House managers and the defense about witnesses they would like to call before making a decision about any particular witness.