I'll give it a shot: I think the chances are not good in a national election for either potential candidate to win at the top of the ticket ... combining them into a single ticket increases the negative odds of conservatives prevailing.
The point offered, there's a long way to go and in this volatile political climate just about anything can happen ... so this conservative is ready -- hopeful, actually -- for a few good surprises.
Sorry, perhaps I'm missing your point, but are you saying that you don't think they can win together because you don't think they win apart? So...they can't win because you don't think they can win? I was hoping for something a little more tangible.