03/20/2012 06:36 pm ET Updated May 20, 2012

Exclusive: GQ Reveals Romney's and Santorum's Secret Service Code Names

By Marc Ambinder, GQ

They are the best kept secrets of any presidential campaign -- until someone overhears a whispered shout into a wrist microphone. Candidates who get Secret Service protection get to choose the code word that they'll be called -- perhaps for the rest of their lives, if they're lucky.

GQ can reveal the names chosen by the top two GOPers: According to multiple campaign sources, Mitt Romney elected to call himself "Javelin." And Rick Santorum chose "Petrus."

Get the Latest Death Race Updates From the Campaign Trail Here

The use of code words to refer to candidates are a throwback to the era when Secret Service and White House Communications Agency communications were not encrypted. The tradition has stuck around. The only real rule the Service has is that the word chosen be comprehensible over the radio and not be similar to someone's else's. That's why code names tend to have two or three strong syllables.

It's tempting to associate a candidate's code word with some aspect of their personality. Sometimes this is true and sometimes it is not. "Petrus" is a biblical allusion -- as in St. Peter, the first pope. (The Latin name is derived from the Greek word for "rock.") Perhaps "Javelin" is a reference to the '60s muscle car made by American Motors Corporation, the company once run by George Romney.

See also: The Best of Jennifer Aniston in GQ

But when reporters tried to ascribe meaning to John McCain's code name in the 2008 campaign -- "Phoenix" -- they were projecting. McCain had the Service choose a name for him. "Phoenix" was chosen randomly, and he liked it. His wife, Cindy, promptly chose "Parasol."

President Obama's code name was disclosed shortly after he was given Secret Service protection in 2007: "Renegade." Wife Michelle is "Renaissance." The First Daughters go by "Radiance and Rosebud." And Vice President Joe Biden chose "Celtic."

Is it irresponsible to talk about code names? Not really, says the Secret Service.

"Call signs are designated jointly by Secret Service and the military (White House Military Office) for communications purposes," said Ed Donovan, the Special Agent in Charge of the government and public affairs shop. "Given modern capabilities to secure communications through encryption, there is no longer any security relevance to protectee call signs."

Donovan would not, however, confirm the names GQ has obtained.

More from GQ:
The 10 Best New Restaurants in America
The 25 Greatest Philanderers in American Political History
A Guide to Republican Candidate Style