Besides tilting the voting population, the effect of all this will be to depress wages, especially for the bottom quartile of the population. The US just got a large increase in the workforce, at the wrong end of it.
It takes a couple of generations for immigrants to catch up in their ability to be productive, assuming that they are able to catch up.
Europe found out the hard way that many of their immigrations could not reach high school in their academic abilities.
There is a quote that I can paraphrase, but the original is better. It says that they use immigration to tamp down on wage increases for the poor.