President Donald Trump speaks next to the $1.3 trillion spending bill in the White House, on Friday, March 23, 2018. Photo: Andrew Harrer/Bloomberg via Getty Images

Earlier this year, President Trump had agreed to trade protection for the Dreamers for funding for his precious border wall, but then he backed away from that agreement; as a result, there is no wall funding. The most recent budget deal in Congress still has no wall funding, and specifically states that any border construction must be see-through fencing. And since the budget needs 60 votes to pass the Senate, and Republicans have only 51 senators, there won’t be a wall unless Trump either gets a lot more Republicans in the Senate or else gets some Democrats to support it.

Unfortunately, Trump does not seem to understand how any of the above works. The Washington Post reports that Trump has been privately insisting that the military should pay for the border wall. “Trump has grown frustrated watching constant TV criticism of the spending deal he signed last week and is determined to find a new way to fund the wall,” the story notes. Of course, Trump had a bipartisan agreement to fund the wall but decided to oppose this deal, and now believes he is entitled to get his side of the deal without giving anything up.

Trump’s proposed mechanism is for the Department of Defense to fund the wall. Trump has tweeted this:

Because of the $700 & $716 Billion Dollars gotten to rebuild our Military, many jobs are created and our Military is again rich. Building a great Border Wall, with drugs (poison) and enemy combatants pouring into our Country, is all about National Defense. Build WALL through M! — Donald J. Trump (@realDonaldTrump) March 25, 2018

(“M” reportedly stands for “military,” not “Mexico.”) And he has brought it up in private repeatedly. “In another such interaction with senior aides last week,” the Post reports, “Trump noted that the Department of Defense was getting so much money as part of the $1.3 trillion spending package that the Pentagon could surely afford the border wall, two White House officials said.”

As the story explains, it’s not a matter of being able to “afford” a spending project; Congress has to authorize spending projects. Just because the Department of Defense has a lot of money does not mean it can legally spend the money on any project the president wants.

One might think that the first time he floated this notion, somebody would have explained what Congress is and why his plan cannot happen. But when Trump is busy firing everybody who treats him like a moron, maybe his aides are skittish about explaining the, uh, constitutional impediments to his concept.