Backlash over his controversial JD Vance-inspired ideological shift has forced a conservative think tank leader to step down, according to a report on Wednesday. The Bulwark's Joshua Tait described how John A. Burtka IV has resigned as president of Intercollegiate Studies Institute after "rebranding itself around JD Vance style pugnaciousness." The organization was founded in Delaware in 1953, and conservative movement voice William F. Buckley J…