Trump's promise to build a "big, beautiful wall" just ran into a big, beautiful lawsuit.

Donald Trump’s pledge to build a “big, beautiful wall” on the Southern border — and to make Mexico pay for it — was one of his most outlandish and controversial campaign promises.

As expected, Mexico has said it’s not paying a penny for the wall, and congressional Republicans have failed to pass funding for construction of the wall. But that hasn’t stopped the Trump administration from moving forward with the pointless plan — and they’re using taxpayer dollars to fund it.

Now, a group of investigative journalists is suing the Trump administration to find out how much money they’ve already blown on the border wall.

The lawsuit stems from a March 2017 Freedom of Information Act (FOIA) request filed by Reveal from The Center for Investigative Reporting. The FOIA request sought records showing how much money had been spent — and how much more would need to be spent — to buy and clear land, and to construct the wall.

The Trump administration refused to turn over the records, so Reveal is suing to find out how much taxpayer funding has already gone towards the wall, which border officers have called an “incredible waste of taxpayer money.”

On Friday, the White House requested roughly $33 billion in funding for border security measures from Congress, including $18 billion just for the wall.

“With so much taxpayer money at stake and few details about how it would be used, we wanted to know what the government had already spent to acquire land and build barriers along the border and where that land was,” Reveal journalist Ziva Branstetter wrote in an article announcing the lawsuit Saturday.

The findings from the lawsuit could make it even harder to pass a bill funding the wall. As Americans see just how much of their money is being wasted, Republicans in Congress may be less likely to sign off on funding. As it is, only 69 of the 292 congressional Republicans gave a clear endorsement of funding the border wall when surveyed this fall.

While Trump says the wall is needed for border security, experts say it won’t do anything to improve national security. Criminal smugglers have said the wall doesn’t worry them, as they use tunnels and other means to transport illicit goods. If needed, they’ll just raise prices to cover any additional costs, but they won’t stop because of a physical barrier.

Not only is the wall pointless — it’s also deeply unpopular. Nearly two-thirds of Americans are opposed to the wall, and opposition is building despite Trump’s efforts.

Now, Trump is facing a barrier of his own: a lawsuit demanding transparency, and an American public that wants to know how their hard earned tax dollars are being spent.