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GQ reported Monday that the Secret Service code names selected by the top two Republican candidates. Mitt Romney selected the name "Javelin," while Rick Santorum opted for "Petrus," which he told reporters while he mingled with a crowd in Illinois Monday night that he selected because it was his grandfather's name in Latin. But it also has biblical significance.

Selecting a codename for Romney became something of a parlor game  on Twitter earlier this year after it was first reported by ABC News that he would receive protection.

He may have selected Javelin, as GQ's Marc Ambinder points out, because it was a make of car by American Motors, the Detroit company once headed by his father.

Romney has not commented on the codename, but Rick Santorum said on Fox News Monday night that he remembers the Javelin and said, smiling, "its an unusual car, so I think it sort of fits."

Secret Service names can stick. President Obama is Renegade and Michelle Obama is Renaissance. At least one Obama biography incorporates "Renegade" into the title. Ronald Reagan was Rawhide, and that's the name of a book about the assassination attempt against Reagan in 1981.

The names are often chosen by the candidates. Even presidential travel gets in on the act. The campaign bus purchased by the Secret Service to shuttle nominees around swing states is called " Stagecoach."