Karl Rove has been making news over the past several weeks by raising the issue of Hillary Clinton's age and health in the context of her likely run for the presidency in 2016. Though Rove has gotten a lot of blow back for his statements, they are having their intended purpose, in that a lot of people are now talking about Clinton's age and health. But ultimately, her age and health will only be issues if they become issues.

What I mean by that is that voters won't be making their voting decisions based on the fact that Clinton will be 69 by Election Day 2016, or that she suffered a concussion in December 2012. Campaigns are incredibly difficult and rigorous -- requiring long hours, lots of travel, study, speaking, interviews -- and very little down time. If Clinton is able to campaign with energy for a sustained period of time and remain in good health, this won't be an issue. If, however, she begins to appear wan and tired at campaign stops, makes careless errors, or suffers another head injury that takes her off the trail, for instance, it may cause more public concern.

In Bill Clinton's 1996 re-election campaign against Bob Dole, for instance, the issue of Dole's age was out there, but became reinforced by events such as his accidental tumble from a stage, which, however unfair, led to photos like this one being displayed on newspaper front pages.

The other way that age can play a role is if 2016 turns out to be a change election year and Clinton is seen as being too representative of the status quo. In 2008, Sen. John McCain's age was an issue because it reinforced the fact that he was representing an unpopular party that had controlled the White House for eight years and he was running against a fresh faced competitor in Barack Obama.

If, by 2016, Americans are itching for a totally new direction, and Republicans nominate one of their younger faces, then Clinton's age may just get lumped in with a sense that if elected, she'd represent more of the same. Of course, if Republicans nominate Jeb Bush -- something that I still can't believe is actually being talked about in real life -- it will be a lot easier for Democrats to neutralize that issue.