US Vice President Joe Biden (L) takes the stage with New York Governor Andrew Cuomo at an event to announce a major reconstruction project of New York's LaGuardia Airport in New York City, July 27, 2015. [Photo/Agencies]

"As the Biden family continues to go through this difficult time, the vice president is focused on his family and immersed in his work," Barkoff said.

Biden's son, Beau, died of brain cancer in May. The younger Biden's death prompted an outpouring of support for the vice president, who also lost a daughter and his first wife in a car accident in 1972.

Since Beau Biden's death, his father has surrounded himself with longtime confidants and former aides who can provide comfort and emotional support - but also have intimate ties to Biden's two previous presidential campaigns.

In recent weeks, several longtime donors, supporters and former staffers have reached out to the vice president and his staff to offer their condolences, as well as to say they'd be on board if he chooses to run.

The speculation around a potential Biden run grew even louder this past week when Fox News reported that Biden chief of staff Steve Ricchetti had met for breakfast with Louis Susman, a prominent Democratic donor and former US ambassador to the United Kingdom. But individuals familiar with the meeting said Susman and Ricchetti are longtime friends and that Susman initiated the meeting.

Biden would bring to the race 36 years of experience in the Senate, as well as a breadth of foreign and domestic policy experience from his years as vice president. He's been a key negotiator for Obama during fiscal fights on Capitol Hill and also the point person for administration policy in Ukraine and Iraq.

However, Biden's freewheeling, undisciplined style has caused headaches for the White House and has long been a concern for Democrats as he has considered the prospect of running in 2016.