The Bolton - Parnas two front offensive is going to get the GOP calling witnesses just to channel the bleeding.
GOP superpacs are all tied together and are all pulling at least half their balances from foreign criminal organizations and from adversary governments and their cutouts. This is the republican community chest. This is the area republican Senators are most desperate investigations do not reach. Without its criminal support, the republican party would be as solvent as a trump casino on its last day.
They have no choice but to piss away their credibility obstructing documents and witnesses to protect their dirty money vulnerabilities. Which is why their credibility, favorability, and electability will all be long gone when their fraud and laundering are exposed months prior to the election.
No one will miss the republican party or its hacks, rats, kooks, operatives, and fanatics.