Almost everyone is pro-border security regardless of their politics. What people are divided over is how to handle those who came here legally on visas and overstayed them, got jobs working in Trump hotels and casinos and for Trump contractors , made homes here , have American citizen children in many cases, and have contributed to the American economy for many years....
Even todays democrats who have been around more than 5 to 10 years were pro border security... and anti immigration to a much greater degree than they are now.
Trump's Mexican rapists and murderers streaming across the Mexican/US border were invented by him to attract votes from his low information support group. If you believe Trump on this, you will believe that Trump is going to build a wall and get Mexico to pay for it. You'll also believe that low skill manufacturing jobs are, as if by magic, going to return to the U.S. if only a big Wall is built. There is really not all that much difference between believing in this Trump bullshit and believing in Jack and the Beanstock.