Flood America with millions-and-millions of people who have no understanding of American history, freedom, or heritage and, who along with the current generation of public school-indoctrinated natural Americans, are being taught to despise all the above. What you then have is not a melting pot, but a polyglot, multicultural, simmering stew pot of chaos, with no cohesive set of values, and no chance of unifying against an increasingly political-elite US federal government tyranny -- a nation, not of citizens, but of subjects, only interested in what benefits are associated with their own tribal membership. There is no more 'equal justice under the law' when their are separate laws associated with the particular tribe to which you belong. That arrangement suits the Political Class in D.C. well -- every tribe clamoring for special consideration of which only the politicians can extend to them. We're being corralled and neutered by our own ignorance and grafting after special consideration based on politically-constructed false premises of "social justice."
I don't know what motivates Marco Rubio, but I do know what motivates John McCain and Chuck Schumer. For Rubio to have allowed himself to be recruited by the likes of these points to either an extraordinary naivety at best, and total lack of character and honesty, at worst.