Jake Tapper, the CNN news personality, is facing a growing chorus of outrage on social media after announcing he’s penning a new book on the “cover-up” of President Biden’s mental decline while in the 46th president was in office.

Mr. Tapper, who’s believed to be CNN’s second highest-paid star after Anderson Cooper, is being called a hypocrite for having aggressively defended Mr. Biden’s mental fitness prior to the election, before saying, after the election, that he was going to expose the cover-up 

The forthcoming book is titled, “Original Sin: President Biden’s Decline, Its Cover-Up, and His Disastrous Choice to Run Again” and is being published by Penguin.  Mr. Tapper is co-authoring the book with Alex Thompson, a White House reporter for Axios who in the year leading up to the election was a lonely voice doing detailed reporting on the White House’s efforts to conceal Mr. Biden’s mental acuity problems.

Mr. Thompson came under enormous pressure from other mainstream media outlets over his reporting, and a book deal he had for a Biden book was canceled by Simon & Schuster a year ago. Now, vindicated for his lonely stand, Mr. Thompson has another book deal with a prestigious publisher, but has partnered with Mr. Tapper, who is already a successful published author.

Many of those commenting on the book deal are ignoring Mr. Thompson’s role and focusing on the role of the much higher-profile Mr. Tapper, who as part of CNN’s liberal talent lineup was a fierce defender of Mr. Biden. Many conservative commentators are accusing Mr. Tapper of inappropriately cashing in with the new tome. They allege that Mr. Tapper himself  was complicit in the cover-up about President Biden’s mental well-being.

“The mother bleeping AUDACITY of you to do this after running 24-7 interference on behalf of him and mocking and attacking every single person who noticed Biden’s decline,” Mollie Hemingway, editor-in-chief of  The Federalist, said in a post on X in response to a post from Mr. Tapper announcing the release of “Original Sin” on February 26.

“The MOTHER. BUH-LEEP-ING. AUDACITY. Have you no decency? Have you NO shame?”

On the same day, many others took to X to excoriate Mr. Tapper, referencing a 2020 clip from his Sunday CNN program, “State of the Union,” in which he lectured then-Trump 2020 campaign adviser Lara Trump for questioning Mr. Biden’s cognitive decline, accusing her of “mocking his stutter” and saying that she had “no standing to diagnose somebody’s cognitive decline.”

“I would think that somebody in the family would be more sensitive to people who do not have medical licenses diagnosing politicians from afar. Plenty of people have diagnosed your father from afar, and I’m sure it offends you,” he said to Ms. Trump, who hit back, saying she was “not diagnosing” the president.

“Tapper then: It’s a conspiracy theory to say Biden has cognitive decline. It’s a stutter. Tapper now: A book on the cover up,” read a post from conservative X account End Wokeness along with the original clip.

Publicity for the new book  says it draws from interviews with over 200 sources. Mr. Tapper and Mr. Thompson now claim that President Biden’s decision to run for re-election was “shockingly narcissistic, self-delusional, and reckless” and that his team and family had lied about his condition and limitations.

“The irony is biting: In the name of defeating what they called an existential threat to democracy, Biden and his inner circle ensured it, tossing aside his implicit promise to serve for only one term, denying the existence of health issues the nation had been watching for years, dooming the Democrats to defeat,” reads a section of a press release for the book.

During a segment last week on his daily program, “The Lead,” Mr. Tapper responded to the criticism swirling online, insisting that he has long inquired about the ex-president’s cognitive abilities with members of the Democratic party and with Mr. Biden himself.

“As viewers of ‘The Lead’ know, I’ve been covering the concerns about President Biden’s age and health for years. I literally asked him about it in October 2022, and we’ve challenged Democrats and White House officials about it,” he said.

His statement has done little to quell the outrage among conservative voices.

“I can’t believe this is real, and he said this with a straight face. Jake Tapper and CNN covered up for Biden’s decline for years. He’s trying to rewrite history,” posted the popular Libs of TikTok social media account and a clip of Mr. Tapper promoting the book on his show.

“Jake Tapper getting ratioed into oblivion promoting his new book on ‘the real story’ of Biden’s mental decline,” RealClearPolitics co-founder Tom Bevan said on X. “He really does have utter contempt for his viewers and thinks they’re all morons.”

The Spectator’s Stephen L. Miller also took to X to slam Mr. Tapper over his response to Ms. Trump.

“Here’s Jake Tapper incensed over Joe Biden’s ‘stutter’ and outraged over claims of Biden’s cognitive decline,” he said along with a clip of the interview with Ms. Trump. “Now he’s cashing in on a book about Biden’s cognitive decline and media cover-up.”

“There is no bottom for these people.”