I think it's a debatable question in a descriptive sense. It's an open question whether people vote primarily in their material self-interest vs ideology etc.

But I think in a normative sense, it would be impossible to avoid questions of ethics or other "ideological" constructs. Even the most materialist analysis contains agents that act in a self-interested manner, and behind that self-interest are ethical or normative preferences that are worthy of examination on an individual basis, as opposed to strictly a collective sociological analysis.