Republicans fighting President Trump's $25 billion border wall and immigration demands will pay a big political price in 2018 and disaster in 2020 if they don't quickly change direction, according to new book on America's populist movement from new Fox News host Laura Ingraham.

"If a wall -- a physical wall -- is not erected along our southern border, the president and his party will pay a severe political price," she warned in Billionaire at the Barricades: The Populist Revolution from Reagan to Trump.

Ingraham, famous for her radio show and Lifezette news and lifestyle site, revealed that during a closed-door GOP meeting on the wall, Republican leaders "laughed out loud at the idea that Trump's border wall would ever be built."

Late Sunday, Trump demanded wall funding and several other major immigration reforms targeting illegals in exchange for a deal with Democrats and Republican moderates to allow some 700,000 recipients of the Obama-era Deferred Action for Childhood Arrivals to remain in the United States.

A new poll, meanwhile, showed support for Trump's demands though support for a border wall has fallen in the general public.

Ingraham, in the book from St. Martin's Press' All Points Books, said the wall is key for the president's supporters and compared it to former President George H.W. Bush's promise to never raise taxes. He did and eventually lost his reelection.

She mocked both parties for fighting the costs of the wall, writing:

"Democrats have never met a spending or building project they didn't like. But now all of sudden they're fiscal hawks? Get real. And the establishment Republicans who cowered in the corner for eight years while [former President] Obama nearly doubled the national debt to $19 trillion dollars now expect us to believe they're courageous penny-pinchers? Spare us."

On Oct. 30 she debuts on Fox at 10 p.m. with "The Ingraham Angle."

Her book also includes recommendations for Trump, suggesting that he focus his attention and that of his communications shop on key programs than can be achieved.

"In Washington, you either control the message or the message controls you. One theme a day communicated clearly and consistently -- that should be Trump's messaging goal."

She also called on the White House to speed up hiring key officials to replace Obama holdovers which she says are thwarting the GOP agenda.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com