A fact that is often overlooked. When Reagan ran against Carter he was 69 and in good health with a lot of energy. Having said that you cannot compare the well-being and robust capacity of a senior citizen with a 48 year old woman (in 2012) who runs every day and is in good shape.
Anybody who supports Sarah Palin knows she is indefatigable, relentless and will never give up.
Yes, I suppose if she were debating Romney in a primary, she could turn the tables on the Reagan quip and tell him she won’t hold his age against him. (Mitt would be almost 66 by the time he took office in 2013.)