Jay Cost takes a look at Hillary's age and notes that at her inauguration in 2017, she would be 69 years old - not exactly a fresh face. That makes her an outlier in the presidential age category the same way Ronald Reagan was. Would that affect her electability?
With prior losers, it is hard to argue that age was a major factor in their final defeats. It may be instead that the qualities that kept those candidates from the White House the first time around contributed to the subsequent losses. If, for instance, Bob Dole, John McCain, and Mitt Romney had been particularly strong candidates, they should have won the party nod the first time they attempted to gain it, when their ages were closer to the historical average. Of course, the same goes for Clinton. She lost to Barack Obama despite massive fundraising, the strong backing (at least initially) of Democratic elites, and universal name recognition. So here is another count against Clinton’s chances—whether her age will be an impediment directly or merely an indication of other impediments she faces.
If the GOP nominate a younger candidate, it should provide an interesting twist on typical electoral campaigns where the GOP nominee is typically significantly older than the Democrat in the race.