I don't think Trump is directly responsible for the Senate Republicans responses.
I've been monitoring the online presence and for weeks now they've been bombarded with "Never voting for you again because you failed to support Trump." Everyone got these messages, from what I've seen but the stronger ones appear to be Senate Republicans who voted to accept the election results.
It's this response that I think is motivating them back onto the Trump train. Besides, it appears they are down with him running again in 2024. Yikes.
Not McConnell, tho. Surprisingly.