"Active grannies" could be the key voter demographic in this year’s presidential election, writes Burson-Marsteller CEO (and former Clinton advisor) Mark Penn in the Politico.

Social security and healthcare are two important issues for this group, who wield particular influence in battle states such as Ohio and Florida. And those issues have not been much discussed of late on the campaign trail.

"And they are not going to vote for an older candidate just because of his age — if anything, they may vote for a candidate who reminds them of their children rather than themselves," Penn writes.