Yes, why are they asking for more witnesses and documents if their case is ironclad?
They wouldn’t be entertaining dilatory motions if they had a case. They would be ready to go to trial.
They want the Senate to do the job for them they failed to do.
The Dems. want this to go on and on as long as they can milk free time from their partners in the media. It is a free political advertisement to reach their base, before an election.