Until the 1990s, American electoral politics were divided ideologically, between the opposing ideas of liberalism and conservatism. Now we have team politics: Democrat versus Republican, my party right or wrong.
Back then, Rush Limbaugh sometimes accused the Republican Party of betraying conservative principles. At the same time, the liberal op-ed writers at the New York Times occasionally took the Democratic Party to task for not being liberal enough.
Those things don't happen now. Americans back their party the same way they back their favorite sports team — with automatic, stupid loyalty.