Barack Obama is literally more popular than Jesus among Democrats. Unfortunately, neither the former president nor any of the party’s 23 candidates currently seeking the 2020 nomination know quite what to do with that information.

Of course, before any serious endorsement conversation can commence, Obama has to finish his book (between rounds of golf and raising millions for his foundation). The writing has been going more slowly than he’d expected, and according to several people who have spoken with him, the 44th president is feeling competitive with his wife, whose own book, Becoming, was the biggest release of 2018 and is on track to be the best-selling memoir in history. Speaking on the condition of anonymity, like others in this story, these sources note he’ll occasionally say in conversation that he’s writing this book himself, while Michelle used a ghostwriter. He’s also trying to balance the historical and political needs of a project that will be up to his standards as a writer, and not 1,000 pages long. Obama’s research process has been intense and convoluted, and it’s still very much ongoing, from the legal pads he had shipped to Marlon Brando’s old island in French Polynesia, where he spent a month in March 2017, to the interviews that aides have been conducting with former members of his administration to jog and build out memories.

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The untitled memoir, which will reportedly begin with his 2004 Democratic National Convention speech and cover his two terms in the White House, won’t be released in 2019, as his publisher, Penguin Random House, had predicted just a few months ago. Dropping the book this year would have helped Obama largely avoid the current political calendar, and a 2020 release threatens to affect the primaries and the party’s campaign against Donald Trump by re-litigating decisions made a decade ago. Another option is to hold it until 2021, when Obama could be either the voice of a party in despair after another defeat, or poised to grab the spotlight from a freshly elected Democratic president. Publishers tend to save their marquee releases to coincide with the holiday-shopping season—Michelle Obama’s book came out a week before Thanksgiving—but doing so in 2020 would mean the book would hit shelves right after Election Day. Katie Hill, an Obama spokesperson, told me that no decisions have been made on the new timing for publication. Hill gave me a statement carefully written to keep the former president’s distance, saying he “welcomes the debate” playing out in the primaries. “The policy debate has shifted since 2007and 2008, and that’s good—it’s evidence of the progress made since then by activists and elected officials at all levels. Big, bold ideas are a sign of the Democratic Party’s strength, and President Obama urges everyone running to be transparent with voters about how these ideas will work in the nitty-gritty, how they’re paid for, and how they’ll affect the lives of all Americans.”

As with Becoming, this book will have more than a standard release. Aides expect Obama to go on tour, with a rush of interviews in which he’ll be expected to talk not just about what he’s written, but about Trump and whatever political news is unfolding that day. When that conversation has come up internally, according to people involved in the discussions, he often says simply, “I can handle it.”

Voters shouldn’t expect him to do almost anything political, or even public, until next year, potentially not until the next Democratic National Convention in Milwaukee. But with former Vice President Joe Biden talking up Obama every chance he gets, the rest of the field is weighing how much they want to present themselves as a restoration of the previous administration, a continuation, or a new approach to politics entirely.

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Obama hasn’t committed to fundraising or other political activity beyond an email that went out last week, signed with his name, announcing the creation of a new general-election fund at the Democratic National Committee. The aide who handled Obama’s political activity through the midterms left earlier this year, and has yet to be replaced. But a source close to the former president told me he is still receiving calls from 2020 hopefuls. The candidates are reportedly looking for more of the wise-elder conversations he hosted through last year’s midterms and beyond, scrounging for advice, and cherishing the fun of getting to talk with a former commander in chief. Some are already on their second or third chat. Obama remains firm that he won’t endorse soon, while aides are stressing that he might get involved later in the process—presumably, the thinking goes, to stop a candidate he sees as too divisive or likely to lose from becoming the nominee. (This hasn’t been specified, but most assume it would be to stop Bernie Sanders.)

Obama and his aides have carefully guarded when and how to deploy him; some have even theorized he could be called on to broker who the 2020 nominee is, if the primaries finish without a clear winner and Democrats face a contested convention. They feel gratified by what happened in the 2018 midterms, when after a year of being dogged by complaints that he’d disappeared, he burst into the final weeks of the campaign season with an intense assault on Trump. As the 2020 race kicked off, Obama stepped out of the way to avoid looming over the conversation, but he is acutely aware that if Biden secures the nomination next summer, that will change. Democrats with ties to Obama expect he will then have to get even more involved next year, both out of a personal friendship and a feeling that the election would become a referendum on his presidency.

The way Biden is campaigning, though, Obama is a regular presence on the trail. On his first day in the race, Biden told reporters that he’d asked Obama not to endorse him (despite firm statements from Obama’s orbit making it clear that he’d decided himself not to endorse his former veep). During his Philadelphia rally this past weekend, Biden said, “Let me stop here and say something we don’t say often enough as a party or as a nation: Barack Obama is a man of extraordinary character, courage, and decency. He was a president our children could look up to and did. He was a great president. I was proud to serve every day as his vice president, but never more proud than on the day we passed health care.”

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“For Biden, it’s a very important piece of his CV; it’s a very important part of his story,” Randi Weingarten, the head of the national teachers’ union, told me in an interview. “For everyone else, they’re talking about how their own biography leads them to certain things.”

Biden wasn’t the first 2020 candidate to invoke the former president’s name on the stump. Asked at his own kickoff press conference in February about past conversations with 44, Senator Cory Booker repurposed a favorite line: “Well, first of all, I just want everybody to know, I miss Obama, and I miss her husband, too.” Beto O’Rourke, who’s attracted a number of top Obama alumni, has been comparing his race to the 2008 campaign. On Tuesday night, during a CNN town hall, O’Rourke called Obama “the greatest president of my lifetime, as far as I’m concerned.”

But to paraphrase a Biden joke from 2007, Biden’s 2020 campaign so far is almost a noun, a verb, and Barack Obama. Biden talks about his old boss in nearly every speech, using him as a validator, a shield from criticism, and a way of summoning nostalgia. During his first week in the race, Biden’s campaign released a video that draws extensively from remarks the former president made in 2017, when presenting Biden with the Presidential Medal of Freedom in their closing days in the White House. It was purposefully made to sound like an endorsement, and produced with the approval of Obama’s office.

Biden advisers declined to comment on the record about how much he’s talking about Obama, wary of seeming like he’s doing it out of crass political calculation. To the Biden team, other presidential candidates not talking about Obama as much as they could is an example of misreading political chatter on Twitter as representing voters overall, and failing to realize how popular Obama actually is among Democrats. And it’s not just Dems: The Democratic super PAC Priorities USA released a new poll this week finding that among registered voters in the key 2020 swing states of Florida, Michigan, Pennsylvania, and Wisconsin, Obama’s approval rating is at 54 percent, way above Trump, who is at 40 percent.

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Two weeks ago, I asked Kamala Harris what she thought of Biden talking about Obama all the time. She told me that she hadn’t kept up with what he has been saying, insisting she didn’t mean that as a dig. Harris noted that her own relationship with Obama goes back further than Biden’s. She was there in 2007 when he announced his candidacy, and she campaigned for him in Iowa later that year. (Left unsaid was that this was when Biden was actively running against Obama.) “I certainly talk about health care in the context of all that President Obama and his administration accomplished, that we need to take it to the next step, that we need to look at how far we’ve come,” Harris replied when I asked why she doesn’t invoke Obama all that much on the trail.

Biden refers to his time in the White House as “the Obama-Biden administration,” and has identified himself as an Obama-Biden Democrat. I asked Harris whether she would consider herself an heir to the Obama legacy; she said no. “I have my own legacy,” Harris told me. “Listen, I was the elected district attorney of San Francisco, I was the elected attorney general of the state of California—twice elected to both positions. And now I’m a United States senator, and only the second black woman elected to the United States Senate,” she said. “I think I’ve earned my own legacy.”

Biden’s remark last week in New Hampshire that Republicans would have an “epiphany” if and when Trump was defeated was mocked as evidence of a man seeing the world through a Vaseline-smeared lens and not up to speed with life in 2019. He’s done nothing to explain how he would have more success than Obama in negotiations with Congress, and instead brings up Obama’s prediction that the GOP “‘fever’ would break” if he were reelected in 2012. (He won, and the fever got hotter.)

Steve Bullock, the Democratic Montana governor who entered the race last week, is also centering his campaign on a promise to win in Republican territory and pass progressive laws with GOP support. Why would he succeed where Obama failed, I asked Bullock over a beer in Montana. “It’s presumptuous of me to compare myself to how any president did,” he told me before pausing and, yes, comparing himself. “I enjoy the interaction with people. I enjoy the interaction with people I even disagree with.”

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Not everyone is eager to talk Obama. Pete Buttigieg, the South Bend, Indiana, mayor who’s earned comparisons to the former president’s out-of-nowhere campaign for the future—and who accepts nearly every interview pitch that comes his way—declined more than a week’s worth of requests for comment for this story. So far on the trail, he’s pushed back on the kind of nostalgia that Biden has promoted. What the 2016 election showed, Buttigieg said a week ago, is that the old way of doing things wasn’t working for many people.

Eric Swalwell, a representative from California running his own long-shot campaign in part on promoting a new approach and a new generation of leadership, said that the time will come for more Obama, but that time isn’t now. “When he engages in the general, it will be like tagging Hulk Hogan into the ring,” Swalwell told me last week. “He is the best force we’ve got to assist our nominee.”

If that’s true, I asked Swalwell, why not talk about Obama right now?

His very fast answer: “I’m running a campaign about the future.”