McConnell has to prevent any testimony in the impeachment trial, because Trump's people don't want to try to defend him in sworn testimony. It was easy for them to not appear before the house investigation because Trump didn't want them to testify, but he wants his people to stand up and vigorously defend him in the trial. Those potential witnesses are still afraid of being caught in lies, or not being energetic enough in their defense of Trump. It's just too much of a chance for them to take. McConnell has to either prevent everybody from testifying, or try to explain why Trump's people are a no show.
Didn't you traitors have full control in the house to present any witnesses you wanted, yet still couldn't manage to present any fact witnesses and just stuck to defamation by Marxist academics?
So we have a faux impeachment, with no crimes or misdemeanors even alleged, put out for the specific purpose of influencing and altering the 2020 election. Gross abuse of power by the house Communists.
To compound it, Nancy Pelosi and her Communist party are violating the Constitution by refusing to move the process to the Senate, obstructing congress.
So these traitor democrats have abused power and obstructed Congress in order to rig the 2020 election.