From an Associated Press-NORC Center for Public Affairs Research poll in December 2021:
About 3 in 10 also worry that more immigration is causing U.S.-born Americans to lose their economic, political and cultural influence. Republicans are more likely than Democrats to fear a loss of influence because of immigration, 36% to 27%. These results are consistent with past polls showing that many Democrats are anxious about immigration. There is a sentiment among many Americans, that “we like immigrants, we just want fewer of them.”
In all, 17% in the poll believe both that native-born Americans are losing influence because of the growing population of immigrants and that a group of people in the country is trying to replace native-born Americans with immigrants who agree with their political views. That number rises to 42% among the quarter of Americans most likely to embrace other conspiracy theories.