Watch out Oprah, there’s a new book club in town.

President Donald Trump did Eric Bolling a solid Tuesday when he retweeted the Fox News host’s post promoting his new book “The Swamp.” Subtitled “Washington’s Murky Pool of Corruption and Cronyism and How Trump Can Drain It,” the tome advertises itself as a history of political cronyism in America. And thanks to POTUS sharing it with his nearly 33 million followers, “The Swamp” has soared up bestseller charts. For instance, it went from 387 to second place on Amazon.com’s bestseller list. Within 24 hours, the tweet has amassed over 22,000 likes.

While Trump’s presidency has been unprecedented in many ways, Bolling’s hardly the first author to have gotten a helpful boost from America’s commander-in-chief. When Barack Obama was running for the presidency in 2008, he was photographed with a copy of journalist Fareed Zakaria’s foreign policy tract “The Post-American World.” The photo was controversial, with some conservative commentators inaccurately claiming that it was an anti-American tome written by a Muslim. But Zakaria wouldn’t have minded: while the book was already on bestseller lists, it peaked at number 2 on the New York Times bestseller list shortly after Obama was seen with it.

Similarly, when Obama was making his cabinet picks shortly after his November 2008 election, historian Doris Kearns Goodwin’s “Team of Rivals” popped up to number 14 on Amazon’s chart of popular books. The biography of Abraham Lincoln was cited by Obama as a guiding influence and just as Lincoln turned to his political rivals to staff his wartime cabinet, Obama too hired former primary rivals like Hillary Clinton and Joe Biden for top jobs in his administration.

Obama’s predecessor, George W. Bush, was also a White House bibliophile. He famously competed with his political consigliere, Karl Rove, over who could read the most number of books yearly. After Bush name checked Soviet dissident-turned-Israeli parliamentarian Natan Sharansky’s “The Case for Democracy” in his second inauguration address, the book too became a hit, winding up as number 15 on the New York Times’ bestseller charts.

Beyond conferring the presidential halo onto these volumes, what explains the most powerful man in the world’s book promotion abilities? It helps that many Presidents are bestselling authors in their own right and know how to keep those bookshelf tills ringing. Thanks to his 1995 memoir “Dreams from My Father,” Obama won a Grammy Award for Best Spoken Word Album. Bush’s recent art book “Portraits of Courage” was a number one Publisher’s Weekly bestseller earlier this year. And while Donald Trump is known for preferring “the shows” to lengthy briefing books, he too is the co-author of 1987’s “The Art of the Deal,” a New York Times bestseller.