WASHINGTON (AP) Speaking to a packed auditorium of enthusiastic young people Tuesday night, Bernie Sanders already seemed to be campaigning for the White House again. But the Vermont senator was appearing at George Washington University as an author not a presidential candidate.
Sanders' new book, "Where We Go From Here," went on sale Tuesday, giving him a fresh opportunity to promote his ideas without going through the formality yet of launching another presidential campaign.
"What I believe from the bottom of my heart is that it is absolutely imperative that Donald Trump not be elected president of the United States of America. And I'm going to do everything that I can to make certain that that does not happen," Sanders said.
He later added that if he concludes he is the strongest candidate to take on Trump, he'll jump into the race.
Regardless of whether Sanders runs, he and virtually every other prominent Democrat considering a 2020 presidential bid are already participating in the book primary.
Julian Castro, the former Housing and Urban Development secretary, has promoted his book, "An Unlikely Journey: Waking up from My American Dream." New York Sen. Kirsten Gillibrand has been on the road touting her children's book, "Bold & Brave: Ten Heroes Who Won Women the Right to Vote." And in January, California Sen. Kamala Harris will release her memoir, "The Truths We Hold: An American Journey," with a picture book memoir to debut around the same time.
And, of course, there's Michelle Obama. The former first lady has repeatedly said she has no plans to run for office, but she's filled arenas and influenced the political conversation as she's promoted her memoir, "Becoming."
Ahead of a 2020 primary that could pit as many as two dozen Democrats against one another, the books offer potential presidential candidates an early opportunity to introduce themselves to voters in a favorable light.
"Every campaign book has to figure out a way in the predictable tsunami of campaign books that will be coming for the 2020 election to distinguish their book and their product and to extend their brand," said Steve Ross, who formerly led Random House's Crown division and worked with authors including former President Barack Obama.
It's a strategy that has served presidential hopefuls from Abraham Lincoln to Donald Trump, who wrote or authorized books that served as platforms for ideas and shaping their image.
John F. Kennedy's "Profiles in Courage" came out in 1955, when he was in his late 30s, and its sketches of political figures who made unpopular decisions presented him as a serious thinker who, like his subjects, would risk his career for the right cause.
Sen. John McCain's career was influenced, in part, by his acclaimed memoir "Faith of My Fathers," which came out in 1999, around the time of his first presidential run. It marked the first time he wrote at length about his time as a prisoner of war in Vietnam, which helped define his public identity.
The deeply personal exploration of race in Barack Obama's "Dreams from My Father" propelled him onto the national scene when it was republished during his 2004 Senate campaign. His follow-up, "The Audacity of Hope," mixed policy ideas and personal reflections to become a vital part of his successful 2008 presidential campaign.
Ross, who is now the president of the Steve Ross Agency LLC, said the quality of the writing is key to a campaign book's success. If a book is well-written, he said, "it's like selling out a theater with a two-hour biopic about your life that's directed by you and starring you, the politician."
"There are a lot of advantages for both the publisher and for the candidate to have a book as a narrative product," he added. "They can't control what The Washington Post and The New York Times and Fox News is going to say about them, but they can control what's between the covers."
With book authorship comes the opportunity for would-be candidates to travel to promote not only their book but also their strategy for the country, said Michael Steel, who was an adviser to former House Speaker John Boehner and to Jeb Bush's 2016 Republican presidential campaign.
"Particularly for the higher-profile potential candidates, it's an opportunity to get out there and talk about your vision and your record - and it's particularly good because in addition to political news outlets, you can talk to softer-edged media outlets," Steel said. "You can go on 'The View,' you can go on the 'Today' show, you can go on radio stations across the country and talk about the book."
Gillibrand appeared on "The View" earlier this month to promote her book, which contains stories of women who fought for the right to vote. In the interview, she said the book was for "little boys and little girls to understand what leadership looks like."
As expected, she was asked about her own aspirations.
Calling it a "very important moral question," Gillibrand told the hosts that she believed she'd been called to fight "as hard as I possibly can" to restore decency and integrity to the country and that she was considering a run.
Steel drew a distinction between the flurry of books that are being released as candidates consider launching campaigns and the books that are released before a presidential run is officially in the works.
"The books that are written before a candidate decides to run are often far more revealing about their actual character and personality and background," Steel said. "Those are also the ones that can occasionally reveal things that the person probably wouldn't have revealed if they were planning to run for president."
AP National Writer Hillel Italie in New York contributed to this report.