the old guard
noun [ S, + sing/pl verb ] disapproving uk/ˌəʊld ˈɡɑːd/ us/ˌoʊld ˈɡɑːrd/
保守派，保守分子
those people in an organization or society who oppose change and whose beliefs and ideas belong to a period in the past
Radical reform was, of course, opposed by the old guard. 激进的改革理所当然遭到了保守派的反对。