https://www.realclearpolitics.com/articles/2018/12/20/it_was_always_about_the_wall_138971.html
The reason a secure borer wall has not been — and may not be — built is not apprehension that it would not work, but rather real fear that it would work only too well.
There was likely never going to be “comprehensive immigration reform” or any deal amnestying the DACA recipients in exchange for building the wall. Democrats in the present political landscape will not consent to a wall. For them, a successful border wall is now considered bad politics in almost every manner imaginable.
Yet 12 years ago, Congress, with broad bipartisan support, passed the Security Fence of Act of 2006. The bill was signed into law by then-President George W. Bush to overwhelming public applause. The stopgap legislation led to some 650 miles of a mostly inexpensive steel fence while still leaving about two-thirds of the 1,950-mile border unfenced.
In those days there were not, as now, nearly 50 million foreign-born immigrants living in the United States, perhaps nearly 15 million of them illegally.
Sheer numbers have radically changed electoral politics. Take California. One out of every four residents in California is foreign-born. Not since 2006 has any California Republican been elected to statewide office.
The solidly blue states of the American Southwest, including Colorado, Nevada and New Mexico, voted red as recently as 2004 for George W. Bush. Progressives understandably conclude that de facto open borders are good long-term politics.