Noun
integrationist (plural integrationists)
An advocate, supporter and/or practitioner of (social) integration, usually aiming for greater equality.
Brexit itself, while depriving the union of the UK's economic power and diplomatic clout, will also, by removing a semi-detached member that always stood at a remove from the integrationist centre, make the union more coherent.” Source: Internet
Smuts was never a racial liberal, still less an integrationist. Source: Internet