Hillary Clinton and Jay Leno are among some celebrities claiming Donald Trump does not have permission to publish letters they wrote to him, which are set to be released in the former president’s upcoming book, Letters to Trump.

Trump is set to release Letters to Trump through Winning Team Publishing on April 25. The book promises to reveal letters sent to Trump by influential figures, including Princess Diana, Ronald Reagan, Richard Nixon, Kim Jong-un, and John F. Kennedy Jr., among others.

However, certain celebrities who have changed their attitude toward Trump since his entrance into the political arena are speaking out against the book. Some even claim it would be unlawful for their letters to be published.

Jay Leno, whose letter to Trump is set to appear in the book, said he did not give Trump permission to make the letter public.

“Jay did not release, nor authorize any use of any letter to Mr. Trump,” a Leno representative told Newsweek.

Entrepreneur Donald Trump on ‘The Tonight Show with Jay Leno’ on January 13, 2004, at the NBC Studios, in Burbank, California. (Photo by Kevin Winter/Getty Images

Clinton spokesperson Nick Merrill said, “of course,” Trump did not seek Clinton’s permission before deciding to make their correspondence public.

“Nothing says deeply-insecure-has-been quite like publishing private correspondence with the hope that people will believe you once garnered respect,” Merrill told Newsweek. “Feels like the adult equivalent of when a toddler proudly presents you with what they’ve done on the potty.”

Oprah Winfrey also said her views on Trump have changed in light of a more than two-decade-old letter she wrote to him that mulled the idea of them sharing a presidential ticket.

“‘I think he’d written a book and said that he wanted me to be his running mate … if he decided to run, and when I heard that this letter is now going to be a part of a book, I thought, ‘Oh, wasn’t that nice of me to write a note,’” Winfrey told CBS.

“That’s what I thought, because I’m always like, Oh, I should write a note. The person did this, or I should write a note,” Winfrey continued. “So I’m really happy that I wrote a note.”

“I might have thought it back then. I might have thought it 23 years ago,” she added. “I’m not thinking it today.”

Despite certain celebrities’ claims they did not permit Trump to publish the letters, the publishing company said they have “either actual or implied consent” for their publication.

“The book comprises of a unique collection of correspondence either from President Trump or from public officials both foreign and domestic, or from private individuals. For those in public office at the time, no copyright protection arises,” a Winning Team Publishing spokesperson said. “For the last category, Winning Team Publishing has either actual or implied consent for their publication.”

Democratic presidential nominee former Secretary of State Hillary Clinton walks off stage as Republican presidential nominee Donald Trump smiles after the third U.S. presidential debate at the Thomas & Mack Center on October 19, 2016, in Las Vegas, Nevada. (Photo by Chip Somodevilla/Getty Images)

Trump responded to reports about Leno and Winfrey’s remarks on his Truth Social platform on Tuesday.

“Jay, you did when you sent it,” Trump said about Leno’s claim that he did not give Trump permission to publish the letter.

Speaking on Winfrey, Trump said, “Neither am I,” in response to her claim that she is “not thinking” about a dual ticket today.

Speaking to Breitbart News about the book, Trump said it will show readers he has lived a “very fascinating life.”

“I think they’re going to see a very fascinating life. I knew them all — and every one of them kissed my ass, and now I only have half of them kissing my ass,” Trump joked to Breitbart News.

Jordan Dixon-Hamilton is a reporter for Breitbart News. Write to him at jdixonhamilton@breitbart.com or follow him on Twitter.