The only authorized biographer of President Trump, who has collected 600 pages of raw quotes from the president, his family, and top aides for a new book due out next week, has received multiple anonymous death threats that law enforcement believe could be from left-wing activists angered he is "separating fact from fiction" about the controversial White House.

New York Times best-selling author Doug Wead told Secrets that the threats also targeted his children and warned that the family will be “bathed in blood” if his new book, "Inside Trump's White House: The Real Story of His Presidency," goes on sale as planned Nov. 26.

“I’ve never been threatened,” said Wead, well-known for a previous book about presidential children, All the Presidents' Children: Triumph and Tragedy in the Lives of America's First Families.

But after receiving the emailed threats, some of which he shared with Secrets, he said, “I feel responsible ... I don’t care about myself because I’m 73, but I worry about my kids.”

Wead has informed the FBI, the local police, and his publisher, Hachette Book Group, and imprint Center Street.

He said that the FBI and law enforcement sources told him that the threats under investigation could be from “left wing activists who are politically motivated" against Trump.

Hachette Editorial Director Kate Hartson told Secrets, “Doug Wead has received threats tied to the publication of his upcoming book. As Doug’s publisher, we take these threats very seriously and are pleased that he is working with law enforcement on this. It’s imperative that the authors we publish are able to express their opinions freely, without fear of intimidation.”

The publisher said it hasn’t experienced death threats for any book in over 40 years. It even offered to “back out” of publishing if Wead wanted. He didn’t.

Wead described his book as “fair” and noted that he has the coveted perch of being the only authorized historian with free access to the White House. He has interviewed the president, top aides, and family members.

"Inside Trump's White House: The Real Story of His Presidency" has special chapters dedicated to the president and the presidential family, including extensive sections on Ivanka Trump and Jared Kushner.

He wrote it in part because news reports about the president and his family differ starkly from what he has witnessed.

Separating Fact from Fiction about @realDonaldTrump's@WhiteHouse :



Are the president and the @FLOTUS estranged? Did Karl Rove, Manafort, and Kellyanne Conway pick Mike Pence as @VP? Is @TiffanyATrump not supportive of her father’s campaign? — Doug Wead (@DougWead) November 4, 2019

“What I discovered inside the Trump bubble was quite different from what had been reported. No, Melania and Donald were not estranged, they were tender lovers, who playfully teased each other,” he blogged this month.

His book also dismisses claims of rivalries and fights in other books that have helped those anti-Trump books boost sales.

The threats surfaced after Wead and his publisher Center Street shared with Secrets Trump’s charge in the book that former President Barack Obama was “treasonous” for spying on his 2016 presidential campaign.

“What they did was treasonous, OK? It was treasonous,” he told Wead. “The interesting thing out of all of this is that we caught them spying on the election. They were spying on my campaign. So you know? What is that all about?” added Trump.

One long death threat email followed that report and included information on Wead and his family that he has kept secret. It was from Belarus and cited the Secrets report.

“I would postpone printing or selling the book temporarily until it is amended on the basis of TRUTH, facts,” said the email. If not, added the email, “blood will be shed, blood from your book will flood your children and their future.”

Another emailed threat read simply, “Wead needs a f---ing bullet in his head.”

Initially, law enforcement warned him against telling his story because it would draw “copycats.” But as the threats piled up, he decided to go public in hopes of scaring off those who might go through with threats.

“Law enforcement thought the sunshine would be good,” Wead said.

The threats could be linked to activists eager to shutdown anything positive said about Trump and his administration, suggested Wead. He has seen several of his speeches posted on Facebook and elsewhere, for example, taken down.

His book has already been printed and is being translated into several languages.