Actually Rowan and Martin lampooned everyone. Now during the 1968 election they asked both Nixon and Humphrey to come on.
Humphrey thought it beneath him and did not do it. Nixon though realized how powerful the medium was and did do it.
“Sock it to me?”
The producer of the show says he beliefs that got Nixon elected because it showed he had a sense of humor and could poke fun of himself. I think that very true. I was kid then but I remember that episode. Nixon was pretty funny.
By the way I don’t know what Rowan and Martin were politically, they always seemed like Republicans to me.
And in the early 70s, Ronald Reagan was on The Dean Martin Celebrity Roast. I think it's still out there on YouTube.