O, Mark Salter!!

McCain wordsmith revealed as "anonymous" author of "O" the novel.

Confirmed by sources, but there were lots of in-plain-sight clues that led to Salter's Maine door.

(Flashback: Page Six touted Salter.)

--Simon and Schuster topper Jonathan Karp was Salter's editor on books he did with Senator McCain.

--Salter has been holed up in Maine since leaving his job in the Senate.

--The descriptions that Karp has given of the author matched Salter.

--Salter's non-denial denial was the closest to a confession of any suspect who was publicly asked.

--There is a story early in the book based on a real-life tale that would have been known only to a McCain campaign insider such as Salter.

Salter declined to comment. Karp declined to directly address Salter's authorship.