The United States Secret Service is slated to start a round-the-clock protection for Republican presidential contenders Donald Trump and Ben Carson which includes assigning them special names.

Secret Service agents newly assigned to protect Trump will be referring to the real-estate magnate and current GOP front-runner as “Mogul,” the Fox News reported Tuesday.

“Eli” is reportedly the special name that the Secret Service has assigned to Carson, a former neurosurgeon who is currently close on Trump’s heel as the runner-up in the Republican field.

Officials familiar with the matter told Fox News that the round-the-clock protection begins for both candidates on Wednesday morning.

The Secret Service, in consultation with the White House Communications Agency, traditionally chooses a letter of the alphabet for a code name for the president, first lady or other high-profile people under the agency’s protection.

The name is not a secret and does not reveal any sensitive details. It's simply a way to have a short, simple name to describe the person among the agents.

Sources close to Trump have confirmed "M" as his letter. The billionaire was given by the Secret Service a list of some 10 names starting with the letter. Trump, in response, sent back a couple of names that he found acceptable, including "Mogul."

Over the years, American presidents have usually been assigned Secret Service code names that match their characteristics. For example, former President Ronald Reagan, who was an actor prior to his presidency, was known as "Rawhide," while Dwight Eisenhower was called "Scorecard" given his love for golf.

President Barack Obama also has his own name and is known as "Renegade" in the agency, a name that officials say he selected after being given a list of potential "R" words.

The code names for former President Bill Clinton and current Democratic front-runner Hillary Clinton are also interesting.

Bill Clinton was given the letter "E" as he prepared to take office, and when he got the name "Eagle," the rest of his immediate family were given names that start with "E" as well in order to make it consistent for the Secret Service.

Hillary was assigned the name “Evergreen,” which she kept through her tenure as a senator and secretary of state and still uses it today as a Democratic presidential candidate.