The Sunday service wraps up and parishioners file into the fellowship hall at Trinity Episcopal Church, an imposing structure in this southern Wisconsin town built out of stones so thick that it seems they could only be moved by deity. Weak coffee burns on a warmer near a wall rack of communal mugs. Sweet goods pack a foldout table – cheese strudel, sticky buns, cinnamon-sugar donuts.

Paula DeRubeis and Anne Wanke stand nearby, chatting above the din of children. They share the same city and the same faith. But the same politics? Not so much.

Ms. DeRubeis is a staunch Democrat. She believes health care is an absolute right – that everyone in America should be covered, even if it means the federal government has to pay for it.