You can't blame everything on population shifts.
Many leftists in Colorado, Idaho, the Deep South, etc. are native born with deep generational roots. But they watch TV. For generations, their families were reared by Donahue, Oprah, Ellen. By all the woke sitcoms and cop shows and soap operas. By CNN and Howard Stern and rap music. And they read the same New York Times bestsellers.
A state doesn't need Californians to turn blue. Just let your kids consume mainstream entertainment.
I had a neighbor from India for a couple of years. Everything she learned about the U.S., she learned from watching Oprah.