conservatives; old guard
Refers to a faction or group that resists change and upholds traditional ways, especially in political or organizational contexts.
The conservatives within the party strongly opposed the reforms.
He is known as a leader of the old guard.
オールドガード and 守旧派 both describe conservative members who resist change, though オールドガード is a borrowed, more casual term while 守旧派 is a more formal, often political label.
Compound of 守旧 (shukyū, 'adhering to old ways') + 派 (ha, 'faction'). The exact historical derivation is uncertain, but it is a modern political term.