http://www.nationalreview.com/articl...licy-even-more
1. The first and most obvious reason is political. The Deferred Action for Childhood Arrivals program, chain migration, sanctuary cities, and citizenship for immigrants living in the country illegally will give the Left political power.
2. The second reason for the Left’s support for virtually unlimited immigration is that one of the most enduring tenets of the Left — from Karl Marx to the present-day Democratic party and left-wing parties in Western Europe — is that the nation-state is an anachronism.
3. The third reason is the power of feeling good about oneself.