If U.S. presidents were chosen by book sales, Ben Carson would soon occupy the Oval Office.

While potential 2016 contenders are busy traversing the country visiting early primary states and courting donors, some have also found time to promote their recently released tomes. Since 2012, at least eight potential 2016 presidential contenders have released books, with Carson — the former neurosurgeon turned conservative superstar — by far the best selling author among them, according to numbers obtained from Nielsen Bookscan.

Carson’s ”One Nation: What We Can All Do To Save America’s Future” has sold a staggering 355,000 copies since its release in May 2014.

Its only real competition has been Hillary Clinton’s “Hard Choices,” which has sold 264,000 copies since its release in June 2014. Though Carson’s book advance has not been released, it likely pales in comparison to Clinton’s reported $14 million, the second highest advance in history for a non-fiction book.

Mike Huckabee comes in third place in the “book sales primary” with his ”God, Guns, Grits and Gravy” selling 53,000 copies since its recent release in January. Scott Walker’s tome “Unintimidated: A Governor’s Story And A Nation’s Challenge” has sold 21,000 copies in hardcover and paperback since its release in Nov. 2013, placing the Wisconsin governor in fourth place.

In 2012, Kentucky Sen. Rand Paul released ”Government Bullies: How Everyday Americans Are Being Harassed, Abused, And Imprisoned By The Feds,” co-authored with his father, former Rep. Ron Paul. It has so far sold 14,000 copies in hardcover and paperback, which is enough to currently garner Paul the fifth place slot.

Near the bottom of the pack is Florida Gov. Jeb Bush, who many consider the current frontrunner — or at least co-frontrunner — for the GOP nomination. His 2013 book “Immigration Wars: Forging An American Solution,” co-authored with Clint Bolick, has so far sold roughly 6,000 books in hardcover and paperback.

His Florida compatriot, Sen. Marco Rubio, released his latest book ”American Dreams: Restoring Economic Opportunity For Everyone” in January, but so far sales have been mediocre. The book has only sold only 5,000 to date.

At the very bottom of the book primary is former Pennsylvania Sen. Rick Santorum, whose 2014 book “Blue Collar Conservatives: Recommitting To An America That Works” has sold a paltry 4,000 copies.

So, do book sales actually tell us anything about the 2016 presidential race? Probably not much, according to Larry Sabato, the head of the University of Virginia’s Center for Politics.
“It says Carson and Clinton made a lot more money than Bush and Rubio,” Sabato told The Daily Caller. “And Carson has very committed backers that may well give him a higher proportion of the votes than some expect. But the GOP nomination? Highly unlikely.”

“50,000 spread over a nation means little,” he added. “5 million? Now we’re talking.”

Nonetheless, the book primary is only going to heat up, with more potential presidential contenders set to release new books soon. Texas Sen. Ted Cruz’s book “A Time for Truth: Reigniting the Miracle of America” is slated for publication in June, while Rand Paul’s new book “Taking A Stand: Moving Beyond Partisan Politics To Unite America” is set to be released in May. Jeb Bush is reportedly planning to release an e-book in the coming months as well.

All book sales numbers are current up to March 8. Nielsen BookScan’s U.S. Consumer Market Panel “currently covers approximately 85% of the print book market,” according to the company.

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