There is an age limit on the low end, and I think there should be an age limit on the high end. There is a reason we expect the vast majority of people to retire at the age of 70. I'm 59, and I can see such a difference in my abilities to when I was in my 30s and 40s. It is harder to learn new things, frustration levels are much lower than they used to be, multitasking is difficult, switching from one topic to another is not seamless, and on and on. Even the most healthy people I know in their 70s are remarkable not because they are the same as they were 30 years before, but because they are physically and mentally better than others in their 70s. We should elect people who are in their prime, not those who are past retirement age. So I am not pleased with Democrats mostly rallying behind Biden and Sanders, even though I prefer either guy a million times over Trump. A country of over 300 million people should be able to find a decent, smart, likeable, middle-aged person to lead the country.