Russia states that they were having communications with Trump's campaign before the election.  If true, this is the #1 reason to reject Trump.

But really, he's almost certain to be inaugurated.  But because he's so undisciplined and dishonest, it would be a miracle for him to make it through the next 4 years without being impeached.  The only way that can happen is with an invertebrate congress, which it appears that we may have, including our own reps.