Gotta scare both parties to actually achieve something.
That is already being done now by those of us in the immigration reduction business. Blacks feel more strongly than whites on reducing immigration, legal and illegal. And there are environmentalists who want to reduce immigration. A number of years ago, a major fight in the Sierra Club broke out about taking a position on immigration. One faction wanted to take a stand on reducing legal immigration. It gained a lot of support until one of the major donors stopped it. They now say they support a policy that helps other countries improve economically and politically so their people stay in their home countries.
This issue really cuts across political lines It did in the UK. It happened in the US in the 1920s.