Weeks shy of his 95th birthday, former President Jimmy Carter said Tuesday he doesn’t believe he could have managed the most powerful office in the world at 80 years old. Carter, who earlier this year became the longest lived chief executive in American history, didn’t tie his comments to any of his fellow Democrats running for president, but two leading 2020 candidates, Joe Biden and Bernie Sanders, would turn 80 during their terms if elected. Biden is 76. Sanders is 78. “I hope there’s an age limit,” Carter said with a laugh as he answered audience questions at his annual...