They essentially have to agree on the rules/witnesses before they begin the proceeding from what I have heard (I think they did that in 1999).
It’s ironic of course considering how we’re being railroaded in the House.
It seems to me unless it is in the Constitution that the Senate can make it’s own rules for the impeachment process as regards to witnesses.
Please resolve the obvious questions:
<>No agreement, then no hearing
<>Simple vote to change the rules
Statutes cannot be changed without the legislative process. But rules can be. Often they are set before the proceedings begin.
Last week on Sunday Morning Futures with Maria Bartiromo, she asked Lindsey Graham about this.
He said:
“We can go to a floor vote if we have to. We can vote by majority to allow subpoenas from the committee.”