A person who is in favor of greatly restricting immigration because it takes jobs away from American citizens is called a nativist.
Nativist refers to the person who is in resistance to acculturation, in other words, it related to person favoring the native inhabitant over immigrants.
Whereas the other terms,
- Sectionalist refers to the person having a regional interest In contrary to nativist.
- Abolitionist refers to a person who is against slavery, and
- Activist refers to the person who takes active participation in the politics.