According to washingtontimes.com, Vice President Joe Biden walked back on his previous statements towards another White House run in 2020 by saying four years is a "lifetime in american politics". Mr. Biden, who is 74, said his age could be an issue if he decided to run again in 2020 and that the political landscape could shift dramatically before the next election. "Age could be very much an issue and it could not be. It depends on the state of my health and the health of whomever is running," he said in an interview on CNN's "State of the Union."
http://www.washingtontimes.com/news/2016/dec/11/biden-tamps-down-2020-speculation-four-years-is-a-/