Win, lose or draw, Mike Castle was always heading into the Delaware Republican primary as a member of an endangered species. Conservative big game hunters like to call them "RINOs." The popular acronym for "Republican in Name Only" has emerged as one of the Tea Party movement's leading epithets of choice, alongside "liberal" and "progressive." The upshot is that big-government establishment Republicans are no safer from conservative wrath than the Democrats whose legislation they so often support. At some point, millions of grassroots conservatives across the country decided there was something wrong, almost abusive, about the right's relationship with the...