This article from the Washington Post discusses the psychology of voting one’s interest verses voting for ones’ party.
Alaska elected a Republican senator and passed a recreational marijuana initiative, along with an increase in the minimum wage. North Dakota elected a Republican congressman and rejected a Personhood amendment. Arkansas, Nebraska, and South Dakota elected a Republican senator and governor, and passed a minimum wage increase. This led Zachary Goldfarb to write: “Americans will vote for Republicans even though they disagree with them on everything.”
My research suggests a key reason why this happened: our partisan identities motivate us far more powerfully than our views about issues. Although voters may insist in the importance of their values and ideologies, they actually care less about policy and more that their team wins.
This “team spirit” is increasingly powerful because our party identities line up with other powerful identities, such as religion and race. Over the last few decades, Republicans have generally grown increasingly white and churchgoing, while Democrats have become more non-white and secular. This sorting of identities makes us care even more about winning, and less about what our government actually gets done.