And in the Clinton case, all of the witnesses had testified before the Senate trial began, and the only issue was whether they would be re-called to testify once more. The substance of what they would say was already known. Here, McConnell is trying to prevent the witnesses from ever testifying, and the public from ever finding out what they have to say.

Funny, this sounds like the House fucked up and wants the Senate to fix it. If the House wanted them to testify all it had to do was try and enforce it via the courts. They chose not to go to court and instead try to pass the blame.