The GOP controlled Senate has had over 3 years to “discover” this coup. They’ve shown no interest in doing that so far. That won’t be changing in a Senate trial. POTUS can call his own witnesses but he’ll be flying solo there, again.
Enough Republicans will side[vote] with the Democrats to convict him. The Republicans hate him as bad if not worse that the Democrats. The Republicans want him out of Office as bad if not worse than the Democrats. There is a reason that the Senate Republicans are remaining silent.