An attorney for the publisher of Michael Wolff’s book Fire and Fury says no retraction or apology is coming.

Donald Trump and his supporters have called the book fiction, and Trump attorney Charles J Harder last week sent a cease-and-desist letter to Henry Holt & Company, threatening legal action.

In a response to Harder that was shared with the Associated Press, Elizabeth McNamara of the firm David Wright Tremaine writes that the book is “an accurate report” and says Harder failed to cite any specific errors.

McNamara writes that former Trump adviser Steve Bannon, whose explosive quotes helped make the book a bestseller, spoke “freely and voluntarily” to author Wolff.

McNamara also writes that should Trump sue, the author and publisher are “quite confident” that Trump political and financial documents would prove “particularly relevant” for the defense.

On Monday, Michael Wolff appeared on MSNBC’s Morning Joe to discuss Fire and Fury: Inside the Trump White House.

In the book, Bannon described a meeting between Donald Trump Jr, senior campaign aides and a Russian lawyer as “treasonous” and “unpatriotic”. Bannon, who is Trump’s former chief strategist, sought to make amends on Sunday, saying in a statement that his description was aimed at former Trump campaign chairman Paul Manafort, not Trump’s son.

Wolff said the comments were “directed directly at Don Jr”.

A White House spokesman said there was no “way back” for Bannon after his comments in the book. Hogan Gidley said he did not “believe there’s any way back for Mr Bannon at this point”.

Gidley spoke to reporters on Monday aboard Air Force One as Trump traveled to Nashville, Tennessee.

The book depicts the 45th president as a leader who does not understand the weight of his office and whose competence is questioned by aides.