So, can a US President pardon a convict who had generously given to the President’s party, and after a direct lobbying campaign on behalf of the convict himself? Yes, he can.
But can a US President revoke a pardon after it becomes too embarrassing even for him? That is less clear.
It is well past time to take the pardon power out of the hands of one person–and especially out of the hands of a lame duck.