Even with illegal immigrants, America is facing declining population, acute labor shortage. A few days ago VP Pence said in a campaign rally about Americans need to have more babies (but not addressing policies that dissuade having babies). Truth is, American population is on the decline. There are plenty of articles on this fact. WaPo June 30, 2017 NYT May 16, 2018 NPR May 17, 2018 Vox May 22, 2018 The Economist Oct 31st 2018 Japan is having a nearly identical crises, they are experiencing some severe labor shortages and anticipated massive shortfalls in tax income, and are actually stretching and bending their visa rules to get around there exceeding strict immigration policies. Republicans know this, and some, like Rubio, are clearly trying to allow for more immigrants in the US, but of source there is enormous resistance to this. Meanwhile industries that rely heavily on immigrant labor (agricultural) and one of the largest Republican supporter will likely be the biggest proponents for increase immigration.