President Trump launched his campaign in 2015 promising, "I will build a great, great wall on our southern border. And I will have Mexico pay for that wall. Mark my words."
Before long, supporters were chanting, "Build the wall!" and Trump was leading them in a call and response. Who will pay for the wall? Mexico.
He told rally-goers that a lot of politicians said it wouldn't be possible to get Mexico to pay for it. "It's going to be so easy; it's going to be so easy," Trump insisted at the time.
Times have changed. Mexico still hasn't paid for it, and the GOP-controlled Congress is debating yet another short-term government funding bill that doesn't contain the $5 billion in wall money over which Trump threatened a government shutdown just a week ago.
His conservative media allies are rebelling, including Laura Ingraham of Fox News, who tweeted Wednesday, "It was supposed to be a 'big beautiful wall' with a 'big beautiful door.' Now it's just an open door with no frame. Unreal."
All of this has Trump offering new and increasingly far-fetched explanations for how the wall will be built and how Mexico will pay for it.
Claim 1: Mexico is paying
In a tweet on Wednesday, Trump offered a new pitch for how the border wall will get done: "Mexico is paying (indirectly) for the Wall through the new USMCA, the replacement for NAFTA! Far more money coming to the U.S.," he wrote. "The United States Military will build the Wall!"
Fact check:
Trump talks about the U.S. Mexico Canada Agreement, or USMCA, like the new trade agreement is already in place. It isn't.
It still has to be ratified by Congress and the legislatures in Mexico and Canada. So, the president's claim that far more money is coming into the U.S. couldn't possibly be true at this point. But will it be true in the future?
"There is no guarantee that on a net basis this trade agreement will produce more economic benefits for the U.S. than NAFTA did in the past," said David Gantz, a law professor at the University of Arizona who focuses on trade agreements. "We don't know yet, and we won't know for several years."
Gantz said when NAFTA was approved, backers oversold the economic benefits to the U.S. And while he argues there are some good improvements and updates in the USMCA, they aren't expected to supercharge economic growth in the U.S.
Asked about possible economic growth as a result of the USMCA bringing in more tax revenue, Monica de Bolle, a senior fellow at the Peterson Institute for International Economics, said, "We have no guarantee that that would happen including because the USMCA is first of all not all that different from NAFTA."
At the White House press briefing earlier this week, press secretary Sarah Huckabee Sanders was asked to explain how the USMCA would pay, even indirectly, for the wall. Here's the exchange:
It's not clear where her math is coming from, though. The White House Council of Economic Advisers hasn't studied the expected economic impacts of the new trade deal yet, and neither has the office of the U.S. Trade Representative, which led negotiations.
If Trump and Sanders are referring to revenue from tariffs, economist de Bolle points out that wouldn't be coming from Mexico, either.
"If you are collecting more revenues, it's because you're making your own consumers pay more for something that they were paying less for before," she said. "You're making the Treasury better off at the expense of your own consumers. It's not at the expense of some other country. It's not."
Claim 2: The military will build the wall
Trump also claims that "because of the tremendous dangers at the Border, including large scale criminal and drug inflow, the United States Military will build the Wall!"
This raises two questions: 1. Does the military have the authority to build the wall? 2. Does it have the money to build the wall?
Fact check:
Earlier this month, in an email to NPR's Tom Bowman, Pentagon spokesman Lt. Col. Jamie Davis addressed the question of legal authority:
As for the funding, that is a much stickier challenge.
"This is not going to happen," said Todd Harrison, a senior fellow at the Center for Strategic and International Studies, who specialized in military budgeting.
Here's why he is making such a bold prediction: "For the military to build the wall, that would qualify as a military construction project, and there's not any money currently appropriated for this — certainly not $5 billion," he said.
So, let's say the president decided the military should take money already set aside for something else and use it to build the wall instead — that would require approval from Congress. Harrison says all the relevant committees in both chambers would have to approve shifting, or "reprogramming," the funds. There are also caps on just how much money can be moved that way.
"If any one of those committees says no, you can't do it," Harrison said.
He has a hard time imagining those committees signing off.
"It would be coming at the expense of other priorities in the military," Harrison said. "Even if they agree with the wall, they would say, 'Hey, don't take our money to pay for it. This money is intended for the military. That's what it was approved for, and that's what we want it to be used for.' "
The process would be the same if the Trump administration wanted to shift funds to the wall from other agencies as well. Congress controls the purse strings.
And that only becomes a harder sell once Democrats take control of the House and the relevant committees in January.
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