Hillary Clinton's upcoming return to the national stage, through a book tour that will keep her in public view until at least December, has revived uncomfortable questions for Democrats about how and why they lost key races in the 2016 election.

Clinton's upcoming book, "What Happened," seeks to address some of those questions from the perspective of the failed Democratic presidential nominee. But her memoir, which will hit shelves on Tuesday, has also stirred discontent among Democrats who would prefer not to reopen the wounds her defeat last year inflicted on the party.

"I think it's a little bit silly to be keeping talking about 2016. We've got too many problems," Sen. Bernie Sanders, I-Vt., said this week of Clinton's book tour.

Excerpts of "What Happened" suggest Clinton plans to argue that Sanders' insurgent challenge during the Democratic primary rested on unrealistic promises and ultimately paved the way for President Trump's successful "Crooked Hillary" attacks.

Clinton's book has reinvigorated debate among Democrats about how much of the blame for President Trump's victory lies with external forces, such as Russian interference and former FBI Director James Comey's 11th hour letter to Congress, and how much responsibility lies with Clinton herself.

The focus of her memoir on dissecting the 2016 election has highlighted the lack of consensus on the left about why Democrats failed to capture the White House and fell short of claiming a Senate majority.

"Clinton is right: Sanders' attacks on her character fed the same narrative as Trump's. They hurt her in the general election," wrote Jill Filipovic, a liberal author, in an op-ed for CNN. "And she's right that running on the Democratic ticket when you're not a Democrat isn't just hypocritical, it can be incredibly damaging. For one thing, it gives a candidate a platform to trash the very party he says he wants to lead."

Rep. Jared Huffman, D-Calif., took to Twitter this week to defend Sanders against Clinton's claims.

"Please Hillary, don't go there," he tweeted.

Democrats have spoken at length about the reasons for their 2016 drubbing, but their organizations have produced few public or comprehensive autopsies of what happened.

House Democrats examined a study of their failure to make significant inroads on the GOP's House majority during the Democratic Congressional Campaign Committee retreat earlier this year, although details of the report remained secret.

Pressure has built on Democratic National Committee Chairman Tom Perez to publish a post-mortem of the election loss similar to the one Republicans performed after their 2012 defeat, even as some within the party call on its leaders to stop dwelling on 2016 and look ahead to the midterm elections instead.

And the impending release of "What Happened" has led to discussions among Democrats about whether they want Clinton to re-emerge as a public face of the left when the party is still searching for its next generation of political stars.

The same concerns have also accompanied former President Barack Obama's expected return to the national conversation in the coming months, given the amount of atrophy that set in for Democrats during his eight years in office.

Clinton's book tour will take her to more than a dozen stops across the country and in Canada starting next week and continuing into December.

Her extended time in the spotlight will almost certainly feature attacks on Trump that could draw the president's ire, as well as blame-casting on Comey and Russia that could inflame existing tensions among her party.