Even before her appointment is announced, informal discussions have begun on resolving a conflict between the Secret Service and the State Department's Diplomatic Security Service, both of which will be assigned to guard her if and when she becomes the nation's top diplomat.
Officials familiar with the matter say the talks revolve around which agency will protect her at home and abroad and who will have the ultimate say in planning her security.
As a former first lady, Clinton is entitled to lifetime protection from the Secret Service. But as secretary of state that task normally would fall to the lesser-known Bureau of Diplomatic Security, the State Department's in-house law enforcement wing.
Neither agency is eager to give up the high-profile job, which will be further complicated by the fact that Clinton's spouse, who might accompany her on overseas missions, is a former president who is also protected by the Secret Service, the officials said.
Clinton spokesman Philippe Reines declined to comment, saying the senator's office will not discuss speculation about her possible nomination or her security arrangements.
Spokesmen for the Secret Service and Diplomatic Security, which routinely refuse to discuss the details of their protective responsibilities, would not comment publicly on the matter.
But other officials at the two agencies acknowledged that Clinton's nomination would create an unprecedented logistical and jurisdictional hurdles that will require significant negotiation to resolve. The officials spoke on condition of anonymity to discuss the internal deliberations.
The officials said Diplomatic Security is concerned about losing its role as bodyguard to the secretary. The Secret Service, meanwhile, is loathe to abandon Clinton, who under legislation passed in 1997 will be the last former first lady to get lifetime protection, they said.
Left unclear is who will decide because such a situation has never arisen before. In the end, it may be up to Clinton herself but the Homeland Security Department, of which the Secret Service is part, may play an advisory role, the officials said.
Clinton can renounce her Secret Service detail, and a compromise might involve a sharing of duty, with Diplomatic Security providing her with protection while she is at work in Washington or on the road but not while she is at home with her husband, the officials said. But such a solution would not address the possibility of Bill Clinton traveling with his wife, especially if he doesn't give up his Secret Service protection.
