Hillary ClintonHillary Diane Rodham ClintonChris Murphy’s profile rises with gun tragedies DNC, RNC step up cyber protections Gun proposal picks up GOP support MORE criticized former Vice President Joe BidenJoseph (Joe) Robinette BidenReport: Biden to write foreword for memoir by transgender activist Biden to Alabama: No more extremist senators Kasich, Biden to hold discussion on bipartisanship 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.

"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 ObamaAll five living former presidents to attend hurricane relief concert Overnight Health Care: Schumer calls for tying ObamaCare fix to children's health insurance | Puerto Rico's water woes worsen | Dems plead for nursing home residents' right to sue Interior moves to delay Obama’s methane leak rule 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 SandersBernard (Bernie) SandersChris Murphy’s profile rises with gun tragedies Clip shows Larry David and Bernie Sanders reacting after discovering they're related For now, Trump dossier creates more questions than answers MORE (I-Vt.), who she defeated in a tough Democratic primary.

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