In politics, summer is traditionally known as the silly season. And nothing right now is sillier — and more hilarious — than the Republican attempts to tag Hillary Clinton as too old for the White House.

The GOP is reportedly road-testing this message — playing the fossil card, as it were — in a bid to delegitimize her potential '16 candidacy and depress the polls that currently show her beating all Republican challengers.

Clinton would be 69 at the next Inauguration, and that purportedly alarms Karl Rove, who says the age message will be "compelling." Louisiana Gov. Bobby Jindal talks in code (barely) when he says that the Democrats have "old, tired candidates." But Mitch McConnell dispensed with code entirely when he quipped not long ago, at a conservative convention, that the '16 Democratic ticket "is shaping up to look like a rerun of The Golden Girls."

Plus, they have the likes of Rush Limbaugh aiding the ageist cause. On the air in April, he wondered aloud whether Americans "want to vote for somebody, a woman, and actually watch a woman get older before their eyes on a daily basis." No Republican dared rebuke him for agism-sexism (big surprise), or to gently point out that male presidents have always gotten older before our eyes.

Out to pasture

So, I have a question: Are these tone-deaf people determined to commit political suicide, or what?

First they alienate younger women — with their talk about "legitimate" rape, and their ongoing legislative war against constitutionally protected abortion — and lose big in 2012, thanks to an historic gender gap. And now, with their anti-Hillary messaging, they seem bent on alienating older women as well. Because the most surefire way to turn off female seniors is to suggest that, by dint of their time on earth, they should be put out to pasture.

Nan Silver, an author-commentator who specializes in psychology and health, nailed it the other day when she opined that an agist GOP message would be a loser: "How hard will it be for the Democrats to maintain the White House in 2016? About as tough as catching fish in a bathtub — as long as the already demographically-challenged Republicans keep up the stupid stuff."

And a few sane Republicans seem to realize this, although they're averse to saying it publicly. As one veteran strategist, who asked not to be identified, told Politico yesterday, "If [Clinton] wins enough older voters in Florida and she wins enough older voters in Ohio, she's president of the United States."

Granted, politicians of a certain age have long been maligned.In 1840, Whig candidate William Henry Harrison took heat for being 67; one Democratic newspaperman suggested that he be forcibly consigned to the glue factory, where he could spend his last days with "a barrel of hard cider and a pension of $2000." (OK, Harrison was old. He caught a cold on Inauguration Day and died a month later. But back in that pre-penicillin era, 67 was the new 100.)

This era is no different. In 1996, Bob Dole was widely mocked for being 72. Democrats not-so-subliminally derided what they called his "old, tired," "disconnected and dysfunctional" rhetoric and the late-night wiseguys chimed in. To wit, David Letterman: "A lot of people would look at a glass as half empty. Bob Dole looks at the glass and says, 'What a great place to put my teeth.'" And 12 years later, geezer-joke magnet John McCain got the same treatment.

Forward-looking symbolism

So if ageist barbs worked against Dole and McCain (or at least contributed to their defeats), why would it be politically stupid to target Clinton? Because her gender is a trump card.

The "old" message works only when it underscores the existing narrative about a candidate. Dole and McCain lost in part because their ideas seemed old or insufficiently forward-looking; the age jokes fed into the predominant narative. Dole muttered about state's rights; nobody cared. McCain cleaved himself to the backward-looking base of his party; swing voters wanted to go forward.

By contrast, Clinton would be the first woman president, and that — by definition — would be an historic step forward. A potentially critical share of older women voters would feel insulted if Republicans were to suggest that her age somehow rendered her irrelevent.

Heck, if Israel can elect Golda Meir as its prime minister — at age 70, more than 44 years ago — it would be politically nuts to harp about a woman's age in 2013 America.

Naturally, Clinton can't just ride her gender into the White House; powerful symbolism aside, she'd also need to craft a forward-looking agenda. And that's where Republicans might be most imperiled. If youngsters like Marco Rubio, Ted Cruz and Rand Paul float reactionary notions that seem tethered to the America of 1950, their whiz kid credentials won't mean squat. It insults younger voters (the most politically progressive age cohort) to assume that they'll vote for a young Republican just because he's young.

As Evan McMorris Santoro of Buzzfeed.com pointed out the other day, one big issue for 2016 is this: "Can anyone under the age of 45 vote for a Republican?"

Beyond the gender symbolism, here's the bottom line: It's not the age that counts, it's the ideas.

Follow me on Twitter, @dickpolman1.