Imagine the following immigration policy, crafted by taking commonly cited objections to immigration at face value. It would include.
1. Open borders for white people, defined as anyone with 7/8ths or greater European ancestry, provable by genealogical records or a DNA test. (I imagine the latter would be commonly used in Latin America.) Justification: obvious.
2. Open borders for middle-Eastern Christians. Justification: they won’t sympathize with the Muslim world or other non-whites.
3. Open borders for Japanese and Koreans. Justification: proven ability to build wealthy, high-trust societies.
4. Open borders for Taiwanese and Hong Kongers who descend from those on the island before 1997. Justification: will be more likely than not to oppose America’s geopolitical enemy.
5. Open borders for non-black women willing to marry and have children with non-Leftist white American men. Justification: such women and their children are unlikely to be anti-white.
6. Immigration quotas for groups like Cubans, whose American co-nationals show a record of pro-capitalist, anti-ethnic bloc voting. Justification: allows people who will probably be good voters into the country, while allowing the flow to be cut off if the new immigrants turn out different from the old immigrants.
7. Immigration quotas for those unlikely to join any existing ethnic bloc-voting constituency or sympathize with geopolitical enemies (Sri Lankan Buddhists, Indonesian and Indian Christians, Yezidis, Indigenous Siberians, etc) Justification: weakens the existing ethnic blocs in the United States.
8. Immigration quotas for atheists in the Muslim world, with atheists of such origin be charged with selecting who will receive the spots and discovering fakers. Justification: while some fakers would slip through, most would be genuinely opposed to Islam and this would drain the Islamic world of human capital.
While you could protest that this agenda would not be politically popular and risks getting struck down as unconstitutional, it need not win any elections.