New York Attorney General Letitia James allegedly slimed the first woman to accuse then-Gov. Andrew Cuomo of sexual misconduct as “not credible” — and flagged initial doubts about a second accuser, his ex-top aide Melissa Derosa claims in her upcoming book.

DeRosa accused James of making the remark about Lindsey Boylan — the woman who opened the floodgates for a wave of Cuomo accusers — even before the attorney general had launched her bombshell sexual misconduct probe in early 2021, an excerpt from the forthcoming memoir shows.

“Melissa, I was at an event yesterday. So many people came up to me and said Lindsey Boylan is not credible,” DeRosa wrote, quoting what she claims James said.

“She is not credible.”

James then allegedly went on to flag her skepticism about Cuomo’s second accuser, Charlotte Bennett, DeRosa writes in the excerpt obtained by The Post.

“On the Charlotte Bennett thing, it is just words,” the attorney general is alleged to have said on the call.

It wasn’t immediately clear when the call took place, but DeRosa writes that it unfolded soon after James’ office had called to inform the Cuomo camp that the AG’s office was taking charge of the investigation.

Cuomo’s longtime secretary and confidante claimed James “attempted to reassure me” about the upcoming probe, with the AG allegedly telling her: “Listen, I will talk to you on the side. I will be engaged with you back and forth.”

Boylan had initially come forward in early 2021 to accuse the now-disgraced governor of kissing her on the lips without warning and suggesting they play strip poker during her time as a state economic development official.

A week later, Bennett then publicly alleged her former boss had asked her inappropriate personal questions, told her he was open to relationships with women in their 20s, and left her feeling that he “wanted to sleep with me.”

Eventually, James’ office issued a scathing 165-page report in August 2021 that substantiated the claims made by Boylan, Bennet and a slew of other women — forcing Cuomo’s resignation and his dramatic fall from grace.

DeRosa, on her part, resigned from her post just weeks before James’ report was handed down.

“The author of this book has a well-earned reputation for dishonesty,” the AG’s spokesperson, Gary Ginsburg, told The Post when asked about DeRosa’s claims in “What’s Left Unsaid: My Life at the Center of Power, Politics & Crisis.”

“Let’s remember this is the very person who lied about the number of people who died in nursing homes during the pandemic,” Ginsburg added, referring to DeRosa’s admission in early 2021 that the Cuomo administration withheld the state’s nursing home COVID-19 death toll from the feds.

Lawyers for Boylan, too, ripped DeRosa, saying she “has no credibility.”

“Ms DeRosa has said this conversation occurred before any investigation or interview took place, which makes it irrelevant. Both the Attorney General’s office and the State Assembly found Mr. Cuomo sexually harassed these women,” the attorneys, Julie Gerchik and Danya Perry, said in a statement.

Meanwhile, DeRosa continued to pile on James elsewhere in her memoir, claiming the attorney general once took a swipe at Mayor Eric Adams by alleging he had “baggage of the female kind.”

While having drinks with James in Lower Manhattan in 2019,

DeRosa wrote that during a 2019 meeting over drinks in Lower Manhattan with James, the state’s top lawyer floated the idea of challenging Adams in the 2021 New York City mayoral race.

“’Madam Attorney General, I really think you should consider throwing your hat in the ring for mayor next year,’ I said, after taking a sip of my Sancerre. Tish’s eyes lit up. I could tell she was flattered,” an excerpt from DeRosa’s book says.

Cuomo’s righthand woman noted that James said she planned to “sit tight for the time being” given she’d only been attorney general for less than a year. But DeRosa goaded James, telling her that having Adams in the mayoral race would make winning “difficult” for the AG given they’d likely split the Brooklyn votes.

“As the words fell out of my mouth, Tish’s face turned sour. I had hit a competitive nerve,” DeRosa wrote.

“’Oh, Melissa, Eric Adams wouldn’t be a concern,’ she said with a half smirk … ‘Let’s just say Eric Adams has baggage. The female kind,’ she said, proud of herself.”

In the memoir, DeRosa quickly distanced herself from the stink bomb, writing: “There have never been any allegations made against Adams, and I have no reason to believe what Tish was intimating was true, then or now. But what Tish James did know is that claims of any kind involving women are explosive.”

A rep for Hizzoner didn’t immediately respond to The Post.