Tell him you love him.
Talk to steer the conversation to other things.
My 92 year old father in law is just the opposite. Used to be a hardcore republican and now watches Rachel Maddow and Keith Olbermann religiously. Is very impressed with Rachel, by the way.
He served in the Pacific during WWII, was a funeral director and business man, Since my own dad passed away, he’s been a decent surrogate.
My dad was the conservative, but I think even he would have been disgusted by what’s been happening in the GOP.