Kamala Harris, presumptive Democratic presidential candidate Joe Biden's choice for vice president, has reportedly chosen a Secret Service code name that is suggested as being a thinly-veiled reference to her trailblazing role as the first black woman, Indian-American, and Jamaican-American woman to run on a major party ticket.

Harris picked the code name "Pioneer" once she was put under Secret Service protection last week after being selected as Biden's running mate in the November elections, according to a law enforcement source cited by CNN.

Choosing a code name from a list vetted by the White House Communications Agency, people under Secret Service protection are believed to typically opt for something that is imbued with personal significance for them.

The code name, which, incidentally, isn’t all that secret, and typically known to the public albeit assigned for security reasons, is often emblematic and offers a glimpse at what that person hopes to achieve.

“Over time, the (Secret Service) protectees have almost taken on the persona of the call sign that they had selected", Jonathan Wackrow, former Secret Service special agent and CNN law enforcement analyst was cited by the outlet as saying.

2020 White House hopeful, former Vice President Joe Biden is said to have stuck with the code name chosen when he was VP under Barack Obama – "Celtic".

His spouse, Jill Biden, also decided her first choice of "Capri" was still good enough.

It's anyone's guess what code name Kamala Harris' husband Douglas Emhoff has chosen, but it's a sure bet that it will also begin with the letter P.

Traditionally, candidates' spouses and family members can choose a name that starts with the same first letter as the candidate's code name.

To prove his point, Wackrow offered a rundown of code names of some other Secret Service protectees.

"With (former President Barack) Obama, 'Renegade' is a great example: how he went against the establishment in some of the things that he had done, and like Barbara Bush, whose call sign was 'Tranquility', embodied the tranquility and peacefulness in a time of war", he said.

Donald Trump's Secret Service code name is "Mogul" and First Lady Melania Trump's is "Muse". Vice President Mike Pence and his Second Lady went with "Hoosier" and "Hummingbird", respectively.