WASHINGTON — Two years ago, the author Michael Wolff parlayed his access to one of President Trump’s most powerful advisers, Stephen K. Bannon, into “Fire and Fury,” a rollicking, behind-the-scenes account of Mr. Trump’s chaotic White House. The book sold more than four million copies, despite lingering questions about its accuracy.
Now, Mr. Wolff is back with a sequel, “Siege: Trump Under Fire,” which appears to rely just as heavily on Mr. Bannon. But the author’s source left the White House in August 2017 and has watched Mr. Trump’s circuslike presidency from afar since. That gives the disclosures in Mr. Wolff’s latest book a secondhand feeling — and one of his most sensational claims drew a quick, emphatic rebuttal.
A spokesman for Robert S. Mueller III, the special counsel in the Russia investigation, denied Mr. Wolff’s claim that in March 2018, Mr. Mueller was preparing to indict the president for obstruction of justice on three counts, including witness tampering. Andrew Weissmann, one of Mr. Mueller’s prosecutors, who Mr. Wolff says led that effort, did not even work on the part of the investigation that focused on obstruction.
In an author’s note, Mr. Wolff said his account of Mr. Mueller’s investigation was based on “internal documents given to me by sources close to the Office of the Special Counsel.” But in a rare on-the-record denial, the special counsel’s spokesman, Peter Carr, said on Tuesday that “the documents described do not exist.”
Mr. Wolff responded in an interview, “My source is impeccable, and I have no doubt about the authenticity and the significance of the documents.”
The criticism of his work puts Mr. Wolff in a familiar position. The White House lashed out after the publication of “Fire and Fury,” calling it “trashy tabloid fiction.” A lawyer for Mr. Trump, Charles J. Harder, tried to block its publication and threatened to sue the publisher, Henry Holt & Company, for libel. Mr. Trump posted on Twitter that the book was “full of lies, misrepresentations and sources that don’t exist.”
Copies of “Siege” have begun circulating in advance of its publication on June 4, and The New York Times obtained one. But the disclosures in the book, first reported on Tuesday by The Guardian, did not provoke the storm of coverage on social media and cable television that helped propel the sales of Mr. Wolff’s last book into the stratosphere.
That may reflect both the questions of accuracy that hung over “Fire and Fury” and a growing jadedness with inside accounts of the Trump White House. Bob Woodward’s best-selling book “Fear” and other accounts have depicted a now-familiar tableau of hapless, scheming aides and an impulsive, erratic president distracted by his legal battles and obsessed with the talking heads on Fox News.
For his first book, Mr. Wolff spent time in the West Wing, often in Mr. Bannon’s office. He does not claim to have had similar access this time, noting that many of his original sources have left the White House.
In his author’s note, Mr. Wolff acknowledged that those sources were not trustworthy. “For the writer,” he said, “interviewing such Janus-faced sources creates a dilemma, for it requires depending on people who lie to also tell the truth — and who might later disavow the truth they have told.”
Mr. Wolff is open about his reliance on Mr. Bannon, whom he thanks in the acknowledgments, describing him as “the most cleareyed interpreter of the Trump phenomenon I know” and “the Virgil anyone might be lucky to have as a guide for a descent into Trumpworld.”
Even after Mr. Bannon left the White House, Mr. Wolff said he exercised considerable power over the president’s agenda. He helped push Mr. Trump into declaring a national emergency to obtain funding for his border wall. Although he quotes Mr. Bannon as saying that Mr. Trump is “not the billionaire he said he was, just another scumbag,” he also thought constantly about going back to him.
The Mueller investigation forms the centerpiece of the book, and Mr. Wolff offers an unusual glimpse into the grand jury, which has heard testimony under a veil of secrecy for months.
“The Mueller grand jurors were more female than male,” he wrote, “more white than black, older rather than younger; they were distinguished most of all by their intensity and focus.”
But Mr. Wolff’s account of the purported draft indictment contained several puzzling elements. He quoted the title of the draft as “UNITED STATES OF AMERICA - against - DONALD J. TRUMP Defendant,” while the usual formulation would be to use the abbreviation “v.” for versus, not “against.” All of the indictments secured by the special counsel use “v.”
Moreover, the purported document says that Mr. Trump could be indicted under three obstruction of justice laws, known as Section 1505, Section 1512 and Section 1513 of Title 18 of the United States code.
Yet around that time, a representative of Mr. Mueller’s told Mr. Trump’s legal team that the president was not under investigation under Section 1505, but rather only under Section 1512, according to a person briefed on that conversation. Mr. Mueller’s representative did not bring up Section 1513, the person said.
That exchange took place after Mr. Trump’s legal team sent Mr. Mueller a letter arguing that Mr. Trump could not have committed obstruction of justice, raising arguments focused exclusively on a technical problem raised by the wording of Section 1505. In response, a representative of Mr. Mueller’s office told Mr. Trump’s lawyers that they were focused on the wrong law, the person said, and should instead look at Section 1512.
Mr. Wolff portrayed Mr. Weissmann as bitterly disappointed by his boss’s refusal to indict the president. But Mr. Weissmann focused on the case against Paul Manafort, Mr. Trump’s campaign chairman, and other defendants. Two other lawyers, James L. Quarles III and Andrew D. Goldstein, were primarily involved in looking at whether Mr. Trump committed obstruction.
On more minor details, Mr. Wolff’s book has the same hit-or-miss quality. Mr. Trump did refer to one of his lawyers, Ty Cobb, as Cy Young — either deliberately or accidentally using the name of another baseball great for his lawyer’s namesake.
But Mr. Wolff also claims that Attorney General William P. Barr viewed taking his job as a “payday,” calculating that if he managed to avoid both a constitutional crisis and the destruction of the Republican Party, “there were many, many future millions in it for him.”
Friends of Mr. Barr’s said that claim was ludicrous. A 69-year-old former corporate lawyer, Mr. Barr listed more than $22 million in assets and income on his financial disclosure form.
“He needed another stint in government like he needed a root canal,” said Jonathan Turley, a longtime friend and professor at George Washington University Law School.