The fact that the party in question is a US Senator tells you how corrupt both parties have become when so much depends on others operating figures like this in a position of power like a puppet for their interests.

I think that's completely wrong. This almost certainly has nothing to do with the parties.

Kentucky's a completely safe "red" state. Trump won by 26 points over Biden in 2020; McConnell trailed him with only a 20 point win in the Senate election. There's no benefit to the party to keeping McConnell in place (and similarly, no benefit to the Democratic party to have Feinstein linger on). In fact, I suspect that if they had their druthers, the GOP would be perfectly happy to have McConnell resign gracefully if he's non compos mentis - Beshear has to appoint a Republican to replace him, so there's no risk of a change in party power in the Senate. He can even announce his retirement effective on the appointment of a replacement, if he want's to make sure there's no gap.

But no one can make a Senator leave. This is not a GOP decision. It's a McConnell decision.