My take on this is that in general, republican voters don't care as much about politics and for that reason are less informed, not less intelligent. I've met my share of trump supporters and there's on thing they all had in common: They weren't aware of half of what is going on in the news (when it comes to politics) and they aren't willing to take what they hear against Trump at face value regardless of the sources.
Having said that, other than the blind follower, you need to find a common ground with a Trump supporter before you can't discuss politics. Once you do, you need to understand what they think about it without criticize their opinion. You can then get into a reasonable conversation because you didn't demonize them.