As the impeachment trial of President Trump began on Thursday, the key question was not whether the Senate would convict Trump (unlikely) but, rather, whether the Senate would call witnesses to testify and whether Trump would let them appear before the chamber.

Over the last two months, Trump has given varying answers about whether he wants witnesses in the Senate trial and whether he would invoke executive privilege to block their testimony. You can watch Trump waver on this in the video above.

In November, Trump said he wanted a Senate trial.

In December, Trump said he would allow administration officials to testify in the Senate, including Secretary of State Mike Pompeo and acting White House chief of staff Mick Mulvaney, both of whom reportedly have knowledge of the alleged Ukraine pressure campaign.

But by January, Trump was less clear about whether he wanted witness testimony and whether he would try to block it.

When asked last week about the possible testimony of former national security adviser John Bolton or a possible deal on impeachment witnesses, Trump said it was up to the Senate to decide. And on Friday, Trump went a step further, indicating he may invoke executive privilege to block the testimony of administration officials.

“I would love everybody to testify. I’d like Mick to testify, I’d like Mike Pompeo to testify, I’d like [former energy secretary] Rick Perry to testify, I want everybody,” Trump said on Friday. “But there are things that you can’t do from the standpoint of executive privilege. You have to maintain that.”

A decision on calling and permitting White House officials to testify is probably only weeks away.