The real reason the Democrats oppose Trump's wall, and have been preventing the construction of a physical barrier for many years, is because they know it's the only thing that prevents a de facto open border with Mexico.  You have no doubt seen old videos of Chuck Schumer and Nancy Pelosi supporting the Secure Fence Act of 2006.  These videos are used to illustrate Chuck's and Nancy's hypocrisy in now opposing Trump's wall (which as proposed is really a tall steel slate fence).

The truth is, the Democrats were just as opposed to any physical barrier then as they are now.  They just dared not admit it to the American people.  And while the Secure Fence Act of 2006 (introduced in the House by New York Republican Peter King) passed with many Democrat votes, the Democrats and cheap-labor Republicans made damn sure the bill was never funded.

While the bill required at least $50B to construct 700 miles of double-layered fencing, Congress ultimately appropriated less than $2.5B (about 5%) to actually construct the barrier.  The passage of the 2006 Secure Fence Act was never about securing the border, but instead to allow Democrats and cheap-labor Republicans to claim they were securing the border while, in reality, keeping it wide open.

The reason the Democrats are intractably opposed to a wall is not, as claimed, because they believe that it doesn't work, but because they know for a fact that it does.  While they drone on about "border security" using "virtual walls," they know all these phrases are just euphemisms for open borders, which is their real objective.

The Democrats have put in place a system of laws, regulations, and court rulings that allow aliens who set foot on U.S. soil to become next to impossible to deport.  Seeing this, foreigners have been flocking to the border, where they promptly turn themselves in to the closest Border Patrol agent.  They are given a notice to appear for a hearing at our overwhelmed immigration courts and released into communities across our nation for citizens to pay for.  Few ever show up for their court date, and even fewer comply with the deportation orders the court issues.

Americans are waking up to the reality that Democrats are determined to transform America through open borders so the electorate better suits their Marxist ideology.  Their template for achieving this is California, where illegal immigration has created a huge underclass of aliens clamoring for ever bigger government ruled by a thin veneer of wealthy elites living behind their own walls and fences and sending their kids to private schools.  What remains of the middle class is busy packing belongings.  Apparently unsatisfied with the pace of California's descent into Venezuela-style, third-world socialism, Governor-Elect Gavin Newsom is promising free health care for illegal aliens.

So when you hear Democrats claiming to support "border security" while opposing a wall, just remember that what they really mean is to make sure the border remains wide open at the expense of American citizens.  

The author hosts Right Now with Jim Daws, a video podcast of news, politics and culture from an American nationalist perspective.  https://twitter.com/RightNowJimDaws