As Steven Levingston recounts in “Barack and Joe,” the partnership between Obama and Biden was an unlikely — and, initially, an uneasy — one. Obama, Levingston writes, was “a young, cerebral African-American who sweated over the precision of his words”; Biden was “an older chummy white guy given to impulsively speaking his mind.” Obama considered Biden a Washington blowhard; listening to one of Biden’s long-winded speeches during a Senate hearing, he wrote a note to an aide: “Shoot. Me. Now.” Biden, for his part, believed Obama to be an impudent tyro. But when Obama needed to choose a running mate, Biden — with his decades of Senate experience and his popularity among white, working-class voters in Rust Belt states — checked the right boxes. During the campaign and then in the White House, their relationship developed and deepened, to the point that, in 2014, when Biden considered taking out a second mortgage to help pay for his son Beau’s brain cancer treatments, Obama told him not to and that, if necessary, he would give Biden the money himself. “Barack and Joe filled in the spaces that were missing in the other man and created something bigger than their separate parts,” Levingston writes. They were “a perfectly matched odd couple.”

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Levingston spends much of “Barack and Joe” dwelling on the public-facing aspect of — and public response to — their “bromance.” He quotes from both men’s Twitter and Instagram accounts; late-night hosts, cable news gasbags and internet meme-makers are all frequently cited. And he attempts to tease out why those who were “observing the president and vice president from a distance” were so invested in Obama and Biden’s relationship. Part of it, Levingston theorizes, was that “America had a weakness for buddy teams. Felix and Oscar. Bert and Ernie. Buzz and Woody.” More interestingly, he argues that Obama and Biden’s partnership, “just by its existence and daily workings … served as a badge of racial harmony.”

What “Barack and Joe” fails to do is shed much new light on the private nature of the two men’s relationship. The nonfiction book editor of The Washington Post, Levingston has combed through the memoirs of Obama administration officials, as well as a number of other journalists’ books, for anecdotes and insights about events that transpired behind the scenes, but he appears to have done little original reporting of his own, interviewing only a handful of people who observed the relationship up close. (Noting that Obama and Biden both declined to be interviewed for his book, Levingston writes, “It has seemed curious to me that, despite their busy schedules, Barack and Joe could not find time to discuss their complicated but largely felicitous relationship.”)

As a result, “Barack and Joe” frequently reads like a rehash of episodes and events that are already well known, with seemingly minor matters being afforded undue significance if only because they’ve previously been well documented. Does the world in 2019, for instance, really need 20 pages on the “Beer Summit” — the 2009 pseudo-event in which Biden and Obama hoisted beers in the Rose Garden with the black Harvard professor Henry Louis Gates and the white Cambridge police officer who mistakenly arrested him? Even worse, “Barack and Joe” is written in a cloying style — “Barack and Joe, no longer opponents, were now able to move into a new phase with each other,” or “Through straight talk over lunch, Barack and Joe resolved their spat” — that seems better suited to a children’s book than a sophisticated political account.

That’s a shame, because with Biden now casting his third presidential run as an attempt to create a third Obama term, it’s never been more important to understand the true and substantive nature of the two men’s political partnership. For all the affectionate lunch outings and bro-hugs that lit up the internet, Obama nonetheless dissuaded Biden from running for president in 2016, instead putting his chips on Hillary Clinton. And in the 2020 race, Obama hasn’t endorsed Biden — or anyone else — in the Democratic primaries. The two men’s friendship may have “moved the nation” as no White House pairing ever had, as Levingston writes. But was it — and should it be — enough to move one of them back into the White House?