A few years ago, I was having a terrible time trying to cast a television series. One role, especially, was nearly impossible to cast. We needed someone to play a grandmother, but a particularly youthful and very much alive kind of grandmother.
You'd think that would be easy to cast. Los Angeles is stuffed to the gills with ageing, still-lovely actresses - you see them gliding around Brentwood in their old Mercedes, dressed in tennis clothes and carrying sensible tote bags, and you think: "Hey! I know that old lady!" But you don't - not really, anyway. She's just a familiar face from a bunch of old movies, or maybe a long-forgotten television series.
That was exactly who we were looking for. So we made a list of ageing starlets, and went for the biggest name we could find. The actress we approached first was the perfect choice: ageless, funny, still popular, with a mantelpiece groaning with awards and - we expected - an eagerness to get back into the spotlight.
We sent her the script. And then we waited. Three days later, she declined. "She just doesn't feel," her agent told us when we spoke, "that she's really old enough for grandmother roles."
She was, at the time, in her very late 70s.
And that's often the problem with casting: the people who are spot on for a role sometimes don't see it; and the actors who are utterly and totally wrong for a part will fight like wildcats to get it. The result, more often than not, is that it's impossible to find an actor who is both right for the part and willing to do it. The ones who won't accept the part are delusional fantasists, and the ones who will are desperate half-talents.
Which, when you think about it, also describes the current race for the Republican presidential nomination.
Let's face it: a presidential campaign is just a more awkward and drawn-out casting session, where the folks who want the job - like Texas Governor Rick Perry and former Massachusetts governor Mitt Romney - seem ill-suited and wrong, and the folks who don't - New Jersey Governor Chris Christie and Indiana Governor Mitch Daniels - just don't seem to understand that they'd be perfect for the job.
This week has seen the political equivalent of waiting to hear from an actress. As the polls swing wildly - from Rick Perry to former pizza delivery executive Herman Cain - only one thing, really, is clear: no one is happy with the casting choices.
In the television business, this isn't really a big problem. Every television series starts as a "pilot" episode - a sample test episode that is focus-grouped, analysed and picked over by terrified executives for several weeks before they give the green light to move forward with the series. It's rare, for instance, for everyone who was in the original pilot cast to make it through the process. The network almost always wants to recast a role or two.
It doesn't always spell disaster, of course. Lisa Kudrow, for instance, who went on to fame and immense fortune as the daffy character Phoebe on the long-running hit, Friends, was originally cast in a role in the pilot of another long-running hit, Frasier.
For some reason, she just didn't seem to fit into the Frasier ensemble, so she was replaced early in the process. That freed her up, nine months later, to accept a role in what eventually became an international television juggernaut.
Usually, though, when an actor is replaced, it's because there was a problem with the audience research.
The focus-group feedback on that particular actor was indifferent, or even negative. People just didn't respond to the person playing the role, and television is an expensive business, so they cut that actor loose. It's important to cover every single contingency. You never know which character is going to emit the most powerful audience appeal, so every single actor has to draw audiences in.
It's the same with politics. As Republican voters keep switching alliances among the candidates, and as they intermittently swoon over those few political figures who refuse to run, they're only doing what television executives do routinely: acting out of insecurity and fear; trying to hedge every possible bet; and desperately hoping that if they wait long enough, the star who refuses to take the part will come to his senses, call his agent and make a deal.
They're going to be waiting a long time.
Rob Long is a writer and producer based in Hollywood