During a private meeting of the most senior Republican senators, GOP leaders “laughed out loud at the idea that Trump’s border wall would ever be built.”

The explosive revelation comes from Laura Ingraham’s new book, Billionaire at the Barricades: The Populist Revolution from Reagan to Trump.

Ingraham reports that her source “was there in the room” when it happened and that the sordid episode is “a reminder that the populist movement that delivered Trump into office must remain vigilant and keep the heat on the GOP Establishment.”

The bestselling author and new Fox News primetime host argues that Republicans will pay an enormous political price if the GOP Establishment succeeds in torpedoing President Trump’s border wall.

“Mark these words: If a wall—a physical wall—is not erected along our southern border, the president and his party will pay a severe political price,” writes Ingraham. She added: “Like George Bush’s promise to ‘Read [his] lips: no new taxes,’ the promise of a border wall was a searing pledge to the American people.”

Billionaire at the Barricades also dismantles arguments against the cost of erecting the border wall.

The notion that Congress can’t find $25 billion—the higher end estimated cost of building the wall—in our nearly $4 trillion annual budget is absurd. Democrats have never met a spending or building project they didn’t like. But now all of a sudden they’re fiscal hawks? Get real. And the Establishment Republicans who cowered in the corner for eight years while Obama nearly doubled the national debt to $19 trillion dollars now expect us to believe they’re courageous penny-pinchers? Spare us.

Ingraham notes that the federal government has blown $25 billion in a single year maintaining vacant and unused buildings—the same higher end cost estimates for the border wall.

“Bottom line: the political fight over the wall is not about money,” writes Ingraham, “it’s about denying Trump and his voters a major victory.”

Ingraham’s “Busting the Barricades” national book tour begins this week.