And the identity of 'Deep Throat' is ... er ... um ...

Let the guessing begin. Again.

Ron Ziegler? He was Richard Nixon's embattled press secretary, best known for his tart denials of any malfeasance in the White House, usually delivered with the look of someone with a mouth full of sauerkraut.

Jonathan Rose? He was a White House attorney who certainly had access to enough information.

Pat Buchanan? In some circles, the fiery former Nixon speechwriter is the latest favorite suspect for the identity of "Deep Throat," the garage-slinking White House source who helped two journalists unravel the greatest political scandal in American history.

If it's another anniversary of the Watergate break-in – and it is, No. 30 – then it must be time to figure out who is the most celebrated anonymous source in American journalism. Again.

Different times have produced different favorites – Al Haig, Nixon's former chief of staff; or L. Patrick Gray III, a former Justice Department official turned head of the FBI.

Now comes Mr. Buchanan, who was a Republican loyalist while in Nixon's speechwriting shop, but who has always had a morally righteous, iconoclastic streak: He was once expelled from college for punching a police officer in a traffic dispute, and, more recently, abandoned the Republican Party to run for president on the Reform Party ticket.

Two of the people who know who Deep Throat is, Watergate reporters Bob Woodward and Carl Bernstein, aren't saying, of course. They have themselves turned a no-comment comment over the years into an art form.

Yet this week, two sources (who aren't anonymous and whom we'll announce in a moment) have put Buchanan on their short list of informants portrayed in the book and movie "All the President's Men." On many counts, the three-time presidential candidate matches the reporters' trail of clues, dropped like cookie crumbs in their book and subsequent public comments. He chain-smoked and drank Scotch, two traits that have been identified with the source. He had a high enough position in the White House, moving from speechwriter to special assistant.

He also lived within walking distance of Mr. Woodward's Washington apartment near Dupont Circle. That's critical in the minds of journalism students from the University of Illinois – one of the sources that has tried to winnow down who the informant might be – because Woodward signaled Deep Throat by placing a flag in a flowerpot on his balcony, which faced an inside courtyard.

Driving by, the source could not have seen it from the street. He would have had to walk. In arranging their signals, which included Deep Throat placing notes inside Woodward's home-delivered newspaper, "You would think they would make it easy on themselves," says William Gaines, a journalism teacher at the University of Illinois.

Three years ago, Mr. Gaines assigned his students the task of identifying "Throat." They combed 16,000 pages of FBI documents, congressional testimony, autobiographies, and personal interviews, putting all the information on an electronic spreadsheet. In the end, they narrowed their list of 72 possible White House officials to seven, including Mr. Rose, Raymond Price, another speechwriter, and Stephen Bull, a Nixon assistant who had access to the president's out basket. All told the students they were not Deep Throat, although Buchanan simply refused to talk with them.

YET it was Buchanan whom these budding journalists put at the top of their list. "One of the things that swayed the students on Buchanan was the trucker's bar," where Woodward and Deep Throat once met, says Gaines. "Of all the candidates, he was a native and knew his way around." He was also on his high school basketball team, tall enough to have left Woodward a note on a high shelf in a parking garage, says Gaines.

Buchanan also makes the short list of former White House counsel John Dean (our second source in today's story). But in an $8 electronic book published by Salon.com yesterday, Mr. Dean, who helped unravel Watergate in searing congressional testimony, refuses to pick a favorite among his final four.

His list closely matches that of the journalism students. It names Buchanan and Messrs. Price and Bull. But Dean, who has made two attempts at this guessing game before, fingers Mr. Ziegler, whom the Illinois students eliminated. Their reason: Deep Throat was known to have imitated Ziegler while meeting with Woodward. If he were Ziegler, why imitate himself? Ziegler has also denied he's Deep Throat.

Yet Dean writes in the e-book: "What the students didn't know however is that Ziegler used to imitate himself briefing the press all the time.... That clue alone has caused one of my former colleagues to become convinced that Ziegler is Deep Throat."

All of this focused research on the shadowy informant – which some journalistic conspiracy theorists continue to insist was a composite – only seems to prove one thing: The guessing will go on. In a 1997 interview with NBC, Woodward said his source was unwilling to reveal his identity because he had not told his colleagues and family members.

But, seriously, does anybody still care about this? "People are always fascinated by unsolved mysteries, and anyone who lived through Watergate and paid attention to it is likely to be curious as to which well-placed government official chose to blow the whistle, and why he did it," says Scott Rosenberg, managing editor of Salon.com.

Maybe so. The video stores that this reporter visited over the weekend were out of copies of "All the President's Men."