WASHINGTON — The acrimony surrounding former White House adviser Steve Bannon's very public break with President Donald Trump is escalating, suggesting a permanent split between the president and the strategist who helped put him in the Oval Office.

The new fissure in the Republican Party cast doubt on Bannon's hopes to foment a movement centered on "Trumpism without Trump."

It already has cost him a key backer in Rebekah Mercer, the billionaire GOP donor and Breitbart co-owner, who distanced her family from him Thursday.

White House officials described the president as furious at Bannon's criticisms, laid out in an explosive new book that quoted the former aide as questioning Trump's competence and describing a meeting at Trump Tower between Donald Trump Jr., Trump campaign aides and a Russian lawyer as "treasonous."