For most of his life, Barone was a Democrat, and he may still consider himself one, but he certainly is conservative nowadays. But, more to the point, he’s a straight shooter and knows more about U.S. politics than anyone alive (even though he was wrong about his 2012 election predictions, as were a lot of us).
It’s wouldn’t make much sense for him to still consider himself a democrat, remaining conservative democrats are mostly of the politically illiterate, dim bulb variety.