Well, that explains it.
An aging population, statistically, will become more conservative overall.
Thus, the Left is importing younger people in droves, in hopes they can sustain their Leftist base, often from countries which lean Left, and ingratiating them with handouts.
And they are hoping they can isolate (and increase) the alphabet people to keep them on the Plantation as well.
They are counting on the illegals to sway that balance.