Hillary ClintonHillary Diane Rodham ClintonTrump complains of 'fake polls' after surveys show him trailing multiple Democratic candidates Hillary Clinton responds to Trump tweets telling Dem lawmakers to 'go back' to their countries The Young Turks' Cenk Uygur: Here's how to choose a president MORE criticized former Vice President Joe BidenJoe BidenTrump complains of 'fake polls' after surveys show him trailing multiple Democratic candidates Biden pitches new subsidies, public option in health care plan The Hill's Morning Report - Presented by JUUL Labs - Trump attack on progressive Dems draws sharp rebuke MORE in her new book for his assessment that Democrats did not focus on the middle class during the presidential race. 

The Democratic nominee defeated by President Trump writes that she found Biden's comments "remarkable" given his own campaigning for her, in which he talked about what she would do for the middle class.

"Joe Biden said the Democratic Party in 2016 'did not talk about what it always stood for — and that was how to maintain a burgeoning middle class,' " Clinton said in her new book, "What Happened," which was obtained by CNN.

"I find this fairly remarkable, considering that Joe himself campaigned for me all over the Midwest and talked plenty about the middle class," she continued. 

Clinton was referring to comments made in May by Biden, in which he criticized Democrats' strategy to win over working-class voters.

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"Because of the negative campaign that [Donald] Trump ran, how much did we hear about that guy making 50,000 bucks on an assembly line, the woman — his wife — making $28,000 as a hostess?" Biden said in May. 

"They have $78,000, two kids, living in a metropolitan area, and they can hardly make it," Biden continued, adding "When was the last time you heard us talk about those people?" 

Biden is not the only figure in Clinton's book to take heat over her shocking loss.  

Clinton offers frank assessments of former FBI Director James Comey and Russian President Vladimir Putin for their actions during the campaign. 

The former nominee even points at former President Barack ObamaBarack Hussein ObamaJulián Castro: 'Everybody knows that the President acts like a white supremacist' Ex-Chicago Mayor Rahm Emanuel joins ABC News as contributor Daily Mail: Ex-British ambassador said Trump left Iran deal to spite Obama MORE, saying he could have put out a stronger response to Russia's efforts to influence the outcome of the election.

And she is critical of Sen. Bernie SandersBernie SandersTrump complains of 'fake polls' after surveys show him trailing multiple Democratic candidates The Hill's Morning Report - Presented by JUUL Labs - Trump attack on progressive Dems draws sharp rebuke Judd Gregg: Counting the costs of Democrats' desires MORE (I-Vt.), who she defeated in a tough Democratic primary.

The book is set to be released on Sept. 12.