Photo: Nicholas Kamm/AFP/Getty Images

Donald Trump ran for president promising to build a wall on the southern border that Mexico would pay for. For the first two years of his presidency, he focused mostly on priorities congressional Republicans cared about (tax cuts, health care, judicial confirmations) and forgot about the wall. At the end of last year, he suddenly realized he was about to lose control of Congress without getting the wall, and shut down the government in the hope that somehow it would lead to a wall. (It didn’t.)

Now President Trump is revealing his fallback plan: pretend he succeeded.

The U.S.-Mexico border runs for nearly 2,000 miles. Early in his campaign, Trump conceded that natural barriers cover half that length. He inherited 654 miles of border fencing, and promised a wall covering a full 654 miles. This would mean upgrading most or all the additional fencing to “wall” status — making it taller, stronger, or wallier — and adding another 350 miles or so of new wall.

He has so far added zero to that total. Yet the wall was never a material infrastructure project, but instead a symbol of defiance and order. Trump is clearly signaling a new stage in which he is abandoning its physical manifestations and conjuring it into reality.

In his speech Monday night in El Paso, Trump responded to the familiar chants of “build that wall!” by assuring the crowd the project was well underway. “Now, you really mean ‘finish that wall,’ because we’ve built a lot of it. It’s ‘finish that wall.’ We have,” he said. “The wall’s being built. It’ll continue. It’s going at a rapid pace.”

Much of the rest of his speech recycled old Trump material bemoaning the lack of a wall and the easy ability of drug traffickers to enter the country. But the shift to the new line was made apparent by the “Finish the Wall” banners flanking the president.

In a speech to police officers Wednesday, Trump elaborated on this imaginary wall. “The wall is very very on its way,” he promised. It is extremely tall — “You’re gonna have to be in extremely good shape to get over this one,” he informed his audience.

As time goes on, just as a child’s imaginary friend becomes more elaborate and fully developed over time, the wall will surely acquire more specific attributes. It will be strong and powerful, beautiful yet forbidding, possibly even festooned with solar panels. In truth, nearly everybody who wanted to believe in the wall in the first place will believe it exists.

After all, Trump told us that without a wall, waves of violent criminals from Latin America would roam the countryside stealing, raping, and murdering honest Americans. Trump’s fans will look around and see no such violence in their midst. It must mean Trump has built the wall.