"What we need are principled conservative career politicians"
"Career politicians" are exactly what this Country DOESN"T need. Our side loses because they back off their principles to appease the rats, not because they are not as devious and corrupt as the rats.
Our side loses because we back off our principles AND because we tend to lack political will and political skill.
I agree that the careerist mentality is a big problem. But I don't think that a career politician must have a careerist (unprincipled) mentality, that amateurs cannot become careerists, or that principled amateurs are enough. You also need toughness, focus, know-how and knowledge. The guy or gal who wants to play in the arena for a few years and then get back to his hometown and his kids' ballgames rarely accomplishes much.