If democrats insist on Bolton then this becomes full blown.
Bidens and the Whistle Blower will have to testify.
No, no, no ... about the Bidens and the Whistleblower.
Perhaps one needs to understand the protection issue of Whistleblowers under the United States Whistleblower Protection Act, established in 1989.
While Democrats and Republicans may insist on individuals to be present at the hearings, it will be decided by a vote of the senators on the matter.