Washington is abuzz with rumors about O, a speculative novel about the Obama presidency penned by "Anonymous." Publisher Simon & Schuster says only that the shadowy scribe has "been in the room with Barack Obama" and has "spent years observing politics." Set in the future during the 2012 presidential election, the 368-page novel is said to mix fiction with reality — much like "Primary Colors," the 1996 novel about Bill Clinton published anonymously by journalist Joe Klein. Beltway pundits are desperate to identify the mystery author before the novel hits shelves later this month. Who are the frontrunners?

1. Joe Klein
Could Klein, now a columnist at Time, have played the same trick again? asks Lloyd Grove at The Daily Beast. Klein says he didn't: "You get to do that only once in a lifetime, I think." Uh, the last time Klein "vehemently denied his involvement" in an anonymous political novel, says Juli Weiner at Vanity Fair, "it turned out he did write [it]." Why believe him now?

2. Robert Gibbs
On the other hand, the publishers' description of the author "fits Gibbs to a T," says Grove, and it is "at minimum, an intriguing coincidence" that the White House press secretary chose to resign just a few weeks before the book's publication. That said, Gibbs has been "rather busy" over the last two years, and "literary flair" isn't his strong suit.

3. Rahm Emanuel
While "the smart money is on Klein, the optimistic money is on former White House chief of staff Rahm Emanuel," says The Guardian, though "Jon Stewart or Stephen Colbert" are also possibilities. Sarah Palin or Glenn Beck? Less likely.

4. Ben Smith
Politico correspondent Ben Smith has been leading a hunt for the anonymous author on his blog, where he and colleague Byron Tau have gathered denials from, among others, Bill Ayers, David Axelrod, David Plouffe, former White House Communications Director Anita Dunn, and New York Times columnist David Brooks. But what about Smith himself? asks Ben Grossman-Cohen at Aggregate Appeal. He fits the description, and has "publicized the upcoming release on multiple occasions." Sorry, responds Smith. "I didn't do it."

5. President Obama
Brian Stelter of The New York Times tells Politico that "Obama himself, ever insistent on controlling his narrative... [may have] penned the book." Is it "far-fetched" to think the president — an "established bestselling author" — is responsible? asks Lloyd Grove at The Daily Beast. "Sure. But it's a possibility worth considering." Not if you're White House spokesperson Bill Burton, who declined to comment on the speculation.

6. President Obama's teleprompter
So the author "knows Obama intimately," sums up Prudence at The Prudence Paine Papers, "tells Obama what to do," and "has written for Obama." The answer is obvious, surely? The "TOTUS" — that is, the "teleprompter of the United States." Mystery solved.