Our quadrennial marathon is on, and nothing says election season better than a campaign-ready memoir. Kamala Harris, who is running, and Joe Biden and Bernie Sanders, who may well run, have each released a book to answer the make-or-break question: “Why are you running for president”, also known as WAYRFP. Make no mistake, coming up short in response can put an end to a candidacy.

In 1979, Edward Kennedy struggled to respond to that query on national television, and never recovered in his bid to unseat Jimmy Carter. Lesson learned. In the run-up to the Bush 88 campaign, the then-vice-president and his staff internalized the significance of WAYRFP. The electorate rewarded their efforts.

Generally, campaign books endeavor to simultaneously show enough leg and sanitize a wannabe’s ambition, aiming to make the candidate interesting without giving too much away. But a political memoir can also say and do plenty. On that score, think The Audacity of Hope, Barack Obama’s profession of political faith from 2006.

In his 2004 keynote speech at the Democratic national convention, the Illinois senator announced: “There is not a liberal America and a conservative America – there is the United States of America. There is not a black America and a white America and Latino America and Asian America – there’s the United States of America.” He used his book to further develop the themes that would underlie his 2008 campaign, namely his life story and an ambivalent relationship with identity politics.

“I reject politics that is based solely on racial identity, gender identity, sexual orientation or victimhood generally,” he wrote, words that would reassure the swing voters who helped him stitch together the largest Democratic plurality in more than 40 years. For good measure, he won an absolute majority of the popular vote each time out and, these days, comes first when it comes to who voters say is the best president in the past 40 years, a 180-degree turnabout from 2014. As for the incumbent, 44% view Donald Trump as the worst.

Not all memoirs are created equal. Some are genuinely poignant, many are personal and policy rollouts, others are cut-and-paste jobs that sandwich a candidate’s recent speeches and essays between two covers, like an aging rock band’s greatest hits album.

Bernie Sanders’ latest, Where We Go from Here, recapitulates his traditional themes and rightly takes credit for defining the fight for the 2016 Democratic nomination, shaping the party’s platform and upping the use of social media as a campaign tool. But he leaves too many questions unanswered.

Disappointingly, Vermont’s septuagenarian junior senator essentially ignores how to pay for the vast expansion of government he expects. In 2016, Sanders backed a plan that one independent thinktank said would lead to steeply reduced growth, “10.56% lower after-tax income for all taxpayers, and a 17.91% lower after-tax income for the wealthiest Americans”. Now, Sanders chooses to rely upon systemic condemnation, confident that in the Age of Trump detail is irrelevant.

We have seen that movie before and it cost Sanders dearly. In the run-up to the 2016 New York primary, he appeared before the New York Daily News editorial board and proved himself unprepared and incapable of meaningfully addressing the role of the Federal Reserve in his proposed breakup of US banks.

Sanders veered and swerved but never delivered a coherent response. For good measure, he also struggled to opine on Obama’s drone-strike policy (“I don’t know the answer to that”) and where he would imprison a captured Isis militant (“Actually, I haven’t thought about it a whole lot”).

The senator had served in Congress since 1991: one would have expected more. After a drubbing by Empire State Democrats, his fate was sealed.

Similarly, Where We Go from Here does not explain what assistance Sanders’ campaign actually received from Russia. A February 2018 criminal indictment against 13 Russian nationals and three businesses alleged that they had “support[ed] Bernie Sanders and then-candidate Donald Trump”. To be clear, Sanders has denied contemporaneous knowledge, saying: “I did not know Russian bots were promoting my campaign.” But he has also argued that Hillary Clinton could have done more to publicize interference by the Kremlin.

Being a populist prophet is not the same as being ready on day one, although as Trump proved, straight answers and command of the facts are not prerequisites to electoral success. Social sentiments and grievance may propel a candidate to victory. Authenticity can carry the day.

If Sanders is the Howard Beale of the Democratic field, the mad-as-hell TV commentator of the 1976 movie Network, then Joe Biden is the uncle you’re happiest to see at Thanksgiving, the one with the jokes whose kids like him and whose wife smiles through unclenched teeth. Although this won’t be enough for Biden to win the nomination if he chooses to run, it is the foundation of his latest book.

Promise Me, Dad is a father’s story, a look back at the last year of the life of Beau Biden, the former vice-president’s oldest son who died of brain cancer in May 2015. Beau was a former Delaware attorney general and Iraq war veteran. Promise Me, Dad melds his battle with cancer with the political events that filled his father’s calendar. It is also the tale of an old-time north-east Democratic pol who understands that culture and coalitions both count.

Among other things, Biden writes of paying his respects to two New York City policemen who were shot dead just for being cops. One was Latino, the other Asian American. Biden’s grief rings genuine: “The assassin’s bullet targeted not just two officers, not just a uniform. It targeted this city.”

For the record, Biden “got it” far more easily than Bill de Blasio, the city’s tin-eared mayor who has also flirted with a 2020 run. As Biden put it, the mayor “seemed happy that it was me representing the administration because he knew I had a close relationship with the police and the civil rights community”.

The book also covers Biden’s globetrotting. He makes resoundingly clear his disdain for Vladimir Putin. Describing a meeting in Moscow, Biden writes, “Mr Prime Minister, I’m looking into your eyes … I don’t think you have a soul.” To which Putin reportedly responded: “We understand each other.”

America awaits the Mueller report.

Harris threads the needle

Last Monday, Martin Luther King Day, the California senator Kamala Harris formally announced her candidacy. Later, Bill O’Reilly, the disgraced former Fox host, tweeted that he would not vote for Harris, citing her denial of “due process” to the supreme court justice Brett Kavanaugh.

In other words, race and gender will continue to buffet our politics. Harris’s book released earlier this month, The Truths We Hold, signals that she will be doubling down rather than backing off.

Harris, who is biracial, does not triangulate when it comes to identity politics. The book’s preface proclaims: “We need to speak truth: that racism, sexism, homophobia, transphobia and antisemitism are real in this country, and we need to confront those forces.” Pages later, she delivers a shout-out to Black Lives Matter.

Further complicating Harris’s road to the White House is her apparent discomfort with Brian Buescher, a Trump nominee for district court in Nebraska, being a member of the Knights of Columbus, a traditional Catholic social organization. For conservatives and others, that will smack of anti-Catholicism and a religious litmus test.

The senator bets that as a former prosecutor she can thread the needle between the demands of the Democrats’ voting core and the wider electorate, moving left in the hope she will bring the center along. While The Truths We Hold disclaims being a policy platform, it is very much that. It offers up an array of middle-class-friendly initiatives, including a call for a tax break, and examines the housing collapse and mortgage crisis.

Here, Harris gets granular and demonstrates a command of her brief. Specifically, she recounts her role in negotiations in the foreclosure abuse settlement. Indeed, she delights in describing how the banks and their lawyers reacted in the course of negotiations. Beyond that, she vents her anger at Fannie Mae and Freddie Mac, the regulators who were asleep at the switch. Or worse.

Harris has had her share of scrapes with the GOP. She has been attacked for her questioning of Rod Rosenstein, the deputy attorney general, and Gen John Kelly, the former secretary of homeland security and second Trump chief of staff. For good measure, Harris writes about how in the administration’s early days she called Kelly at home about the initial travel ban. Kelly sounded none too happy.

The latest polls show Trump beatable. Harris has buzz, Biden has doubts, Sanders has memories. Over time, what they wrote will be less remembered than the fact that they each wrote a book – except during debate prep. Election day 2020 is closer than we realize.