The 72-year-old said his decision on whether to enter the race will hinge on whether he and his family can find the “emotional energy to run.”
The veteran politician has endured a tumultuous time in personal life following the death of his son, Beau. The 46-year-old, a former Delaware attorney general and national guardsman, died of brain cancer in May.
It has been unclear whether Mr Biden intended to seek his party’s candidacy, but yesterday he gave his most extensive remarks yet about entering a primary race that includes frontrunner Hillary Clinton and other long-shot candidates including Bernie Sanders. If he goes ahead and throws his hat into the ring, Biden’s entry would shake up the campaign at a time when some Democrats would like to see more options.
Ms Clinton has locked up much of the Democratic establishment and few expected Mr Biden to enter the race. But the former secretary of state’s recent slide in Democratic primary polls and questions surrounding her use of a private email account and server while at the State Department have prompted the vice-president to explore a campaign to succeed President Barack Obama.
Speaking at a foreign policy address at an Atlanta synagogue, Mr Biden gave a candid answer to a question from the floor about his prospects. “Unless I can go to my party and the American people and say that I am able to devote my whole heart and my whole soul to this endeavour, it would not be appropriate,” he said.
He said based on his previous experiences, there was “no way to put a timetable on it”. But he added: “If I can reach that conclusion and we can do it in a fashion that would still make it viable, I would not hesitate.”
Capping a day that saw Mr Biden defend the Obama administration’s work to forge a nuclear agreement with Iran, the vice-president made clear family came first.
“The most relevant factor in my decision is whether my family and I have the emotional energy to run,” he said in response to a question posed by his longtime friend, Stuart Eizenstat, a former US ambassador to the European Union.
Democrats have said Mr Biden is likely to make a decision this month. The first Democratic presidential debate is on 13 October, giving him a strong incentive to make up his mind before the first televised encounter of the primary campaign.
If Mr Biden joined the field, he would be closely associated with President Obama, who maintains strong support among rank-and-file Democrats. The vice-president has also signalled that he would seek to champion progressive policies, recently meeting Senator Elizabeth Warren, a favourite of liberals.