Its the Law.
The sole purpose of the Secret Service agents are to protect the president. Whoever protects them is irrelevant and quite frankly not needed. People don't plan assassination to kill Secret Service agents, because of how quick people can act. With only 1 (maybe 2) shot, you need to kill the most important figure there, which is usually the president.
The people who protect the U.S. President, Vice President and their families are called the Secret Service.
The Secret Service protects the President of the United States, as directed by Congress. Protecting the president is one of the key missions of the Secret Service.
In the US it is the secret service. They are part of the Treasury Department. In other countries then various government or military departments carry out a similar role.
President Abraham Lincoln
No
The US Secret Service is tasked with keeping the president safe and secure. Details on his protection detail and on the protection of the white house in general are not released to the public.See the reference for more details
Harry Thurman
It's a slang expression usually referring to a group of protective guards, or bodyguards surrounding someone they are assigned to protect. (e.g.: the US Secret Service detail that protects the President)
Bill Clinton
As per the last regulation of the secret service they maybe the future guards of the US President.
The Secret Service Division was created on July 5, 1865 by the treasury department months after Lincolns assassination. At that time they were not established to help protect the president. it wasnt until 1901 after president McKinley was killed that congress asked the US Secret Service to take on the reponsibility of protecting the president. they were run as a branch of the treasury department until 2002 when they were transferred from the department of treasury to newly created department of homeland security. See the related links for more details.