Hillary Clinton's upcoming book will double down on Russia's interference and James Comey's involvement in her stunning election defeat, according to sources familiar with the memoir.

Privately, Clinton has told friends and longtime associates that she "wants the whole story out there" as she rushes to tweak and put the finishing touches on the book due out in September.

"She really believes that's why she lost, and she wants to explain why in no uncertain terms," one longtime ally said. "She wants the whole story out there from her own perspective. I think a lot of people are going to be really surprised by how much she reveals."

The ally said the book of personal essays will be a "bombshell."

The memoir's focus on how Russia and Comey, the former FBI director fired earlier this year by President Trump, cost Clinton the White House would run counter to recent messaging from Senate Minority Leader Charles Schumer (D-N.Y.) and other Democrats about the party's disappointing 2016 results.

"When you lose to somebody who has 40 percent popularity, you don't blame other things - Comey, Russia - you blame yourself," Schumer told The Washington Post earlier this week. "So what did we do wrong? People didn't know what we stood for, just that we were against Trump. And still believe that."

Schumer, who on Monday unveiled the congressional Democrats' new message of "A Better Deal," has been in the middle of discussions on how the party should rebuild and rebrand itself. It is a message with an implicit criticism of Clinton.

Other Democrats including former Vice President Joe Biden have also criticized Clinton's message during the 2016 cycle.

"What happened was that this was the first campaign that I can recall where my party did not talk about what it always stood for - and that was how to maintain a burgeoning middle class," Biden said in March at the University of Pennsylvania, where he launched the Penn Biden Center for Diplomacy and Global Engagement. "You didn't hear a single solitary sentence in the last campaign about that guy working on the assembly line making $60,000 a year and a wife making $32,000 as a hostess."

Biden took it a step further at a Las Vegas hedge fund conference in May, saying: "I never thought she was a great candidate. I thought I was a great candidate."

While the book will zero in on Russia and Comey - which Clinton has said are the two biggest contributing factors to her loss - it will also examine other factors she blames for a role in her defeat, including sexism and misogyny.

"We need to pull it out and put it in the bright light," the former secretary of State said last month at BookExpo, one of the nation's largest gatherings of publishing executives.

Cary Goldstein, who has been heading up the publicity for the book at Simon & Schuster, declined to comment for this story.

Clinton has been toiling on the book with her chief speechwriter, Dan Schwerin, who helped write her last book, "Hard Choices." Schwerin also wrote many of the speeches Clinton gave on the campaign trail and during her years at the State Department. Schwerin, who lives in California, has been flying back to the East Coast every few weeks to work alongside Clinton.

At a Recode tech conference in May, Clinton said, "I take responsibility for every decision I make - but that's not why I lost" - a sentiment she has also told allies.

"She believes she would have won and that Russia and Comey ultimately brought her down," one longtime adviser said. "She feels validated by all the news circulating out there about Russia."

While Clinton has been wrapping up her book, she has been working quietly on helping Democrats win future elections. She's been working with Howard Dean, along with a small group of aides who have spent much of their time checking in with states and organizations to find out what their challenges are and how she can be most helpful.

Earlier this year, she launched a PAC, Onward Together, with the intention of helping congressional Democratic candidates in 2018.

"She wants to make sure the resources coming in to Onward Together have maximum impact," said one source familiar with the process. "She's playing the long game."