They forget the childhood lesson about people not being betteror worse because of what they wear or own, and let themselves become bitter and resentful.
The argument, based on the bitter experience of 2009, went like this: Better to have 54 or 55 Democrats who might actually want to get something done than to worry about building a super-majority on the "strength" of conservative members who enthusiastically support unnecessary wars, free trade and misguided domestic economic policies.