President Donald Trump has said he feels “young” and “vibrant” at the age of 72 and thinks he can beat 76-year-old Joe Biden “easily”.

A reporter asked Mr Trump at the White House on Friday how old is too old to be president of the United States.

Mr Trump said: “I just feel like a young man. I’m so young. I can’t believe it.

“I’m a young vibrant man.”

Election 2020 Joe Biden
Joe Biden is 76 (Jessica Griffin/AP)

Then he smiled and said he was not sure about Democratic presidential contender Mr Biden, the second oldest contender in the race behind Bernie Sanders, who is 77.

Mr Trump said: “I look at Joe. I don’t know about him.”

But he added that he would never say anyone is too old to be president.

Mr Biden said he has no plans to limit himself to one term if he is elected president in 2020.

Barack Obama’s former vice president told ABC’s The View that his age is a “legitimate question” and that voters can decide whether he is up to the demands of the presidency.

Mr Biden would be the oldest president in American history.

He said he hopes to show age has brought “wisdom and experience that can make things a lot better”.