Vice President Joe Biden said he will decide by the summer of 2015 if he will make a third run for the US presidency.

"There may be reasons I don't run but there's no obvious reason for me why I think I should not run," Biden said in an interview aired on Friday on CNN's "New Day" program.

Former Secretary of State Hillary Clinton is the early front-runner for the Democratic presidential nomination in 2016, with a 61 percentage point lead over Biden in a Washington Post-ABC News poll last month. Clinton has not announced if she will run.

Biden, 71, who represented Delaware in the Senate for 36 years before becoming vice president in 2009, first sought the Democratic nomination in 1988 but left the race amid accusations he plagiarized a speech by a British parliamentarian.

He ran again in 2008 but dropped out in January of that year and took the No. 2 spot on the ticket with eventual winner Barack Obama.

Asked in the CNN interview when he would make a decision on a 2016 campaign, Biden said, "Realistically, a year this summer."

"For me, the decision to run or not run is going to be determined by me as to whether I am the best qualified person to focus on the two things I've spent my whole life on – giving ordinary people a fighting chance to make it and a sound foreign policy that's based on rational interests of the United States," he said.