I will build a great, great wall on our southern border. And I will have Mexico pay for that wall.
That promise became one of the hallmarks of his campaign, but got watered down in the Executive Order Trump issued on January 25, 2017 shortly after he took office:
"Wall" shall mean a contiguous, physical wall or other similarly secure, contiguous, and impassable physical barrier.
Parse the "other" substitution: Trump is now talking about building something other than a wall, "similarly secure" doesn't mean secure, "similarly impassable" doesn't mean impassable, and contiguous doesn't say for how far. Then here's what he said on Twitter this past week on April 23, 2017:
Eventually, but at a later date so we can get started early, Mexico will be paying, in some form, for the badly needed border wall.
The water is getting pretty murky with "eventually" and "in some form" as Trump's response to Mexico's highly predictable refusal to pay for his big, beautiful border wall. And Trump's attempt this past week to get funding from Congress has also failed, so there will be no "early start". Ann Coulter is livid but then she's no Yoda:
