CANDIDATES’ DEBATES have since 1960 become indispensable media elements in a presidential campaign — and so too have the full dress-rehearsals held in secret before them.

Last night’s first-of-three prompted me to tally up how many role-playing exercises, across three continents, I have engaged in ahead of such broadcasts.    

It turns out that… counting all my “appearances” as either a politician in a mano-a-mano confrontation with a rival, or as moderator for a panel-grilling, or as a TV network’s single ‘grand inquisitor’ on whom a candidate needs to sharpen his chops, and several times, too, as a politician with the task of upping the inquisitor’s game … the total comes to about 80 of these intense and demanding sessions.

If there’s one lesson for me that emerged from them all — and I was reminded of this as I watched last night — it is that some politicians can be well-prepped for these high-visibility bouts … and others simply cannot.

And the preppers matter too. Front-rank among those with Barack Obama was the thoughtful and somewhat dour Massachusetts senator John Kerry — a failed presidential candidate himself of course. I doubt that he performed a convincingly punchy turn as stand-in for the newly-energized Massachusetts ex-governor Mitt Romney, while the Obama team practiced hard in that weird, other-worldly setting of the Westin Resort & Spa, hugging the 10-mile “shoreline” of the artificial body of water called Lake Las Vegas. The place has always been other-wordly at the best of times — now, recession-blighted as it is, it appears downright moonscape-ish.

Probably more realistic at playing Obama for Romney (in about the fourth round of going through their paces) was Ohio’s Senator Rob Portman, and their version of an isolation chamber was the Renaissance Denver Hotel, sustained in part by some ostentatiously purchased take-out from Chipotle Mexican Grill. Insulation from the real world is always a hallmark of these sessions.

My own most other-worldly setting for prep-work was Portmeirion, a total fantasy village built in Italian style on the north Wales coast — and, maybe pointedly, the film-location for The Prisoner, that cult TV series starring and often written and directed by Patrick McGoohan. My team and I were getting ready for an electoral showdown on TV to be conducted the following week hundreds of miles away in London. I’m glad to say that for us, on that occasion, all participants were highly “preppable” … kept closely to the game-plan … and in the end were rewarded by a broadcast (tied to a now long-forgotten British election) that was a huge relief for everyone involved, including the pols.

But one of the commonest traps I have observed befalling the unpreppable — anywhere in the world — has been their effort to so mightily master the detail of their briefing-books that they lose sight of their overarching strategy for the contest.

Both contenders last night, evidently drenched in detail from those books — showed that tendency to lose sight of the bigger game-plan. In Romney’s case the strategy — as hammered out with advisers like campaign manager Matt Rhoades, longtime aides Beth Myers and Eric Fehrnstrom, and senior strategist Stuart Stevens — was to highlight Obama’s failure at delivering a full national recovery, while displaying the challenger himself as a believable – and, importantly, a humanely understanding – leader who could address the nation’s needs better.

Romney did stick to that strategic track (he remembered, if a little over-transparently, those incidental stump-tour encounters with real people, as in “I was in Dayton, Ohio, and a woman grabbed my arm, and she said, I’ve been out of work since May. Can you help me?“) but that well-poised pose lasted no longer than 25 minutes into the total of 90 minutes.

After that he got deep into a repetitious lecture mode that prompted even The New York Times – never a media outlet to sneer at hints of intellectualism – to headline the encounter as having the “Feel of Seminar.”

Not that Obama – the university professor, remember – was much different. He certainly contributed in spades to that somnolent seminar effect.

The presidential strategy – guided quietly but doggedly as before, and as ever, by David Axelrod – had been to portray confidently the rescue from complete economic disaster achieved by the Obama administration since 2008 — and simultaneously color the upstart as a reckless, uncaring destroyer of cherished middle-class American values and institutions.

But Obama’s bogging-down came when he repeatedly tried to tar Romney with the inevitable effect of his planned 20 percent cut in all marginal tax rates — that is, a $5 trillion reduction in tax revenue and consequently a higher tax burden on many ordinary voters.

When Romney’s response was the easiest rhetorical ploy of all — simply to deny that it’s what he intends – Obama kept on trying to argue the case in detail. A far better switch in tactics – embraced within the overall Lake Las Vegas strategy, without doubt – would have been to return to the big-gun argument: along the lines of … “Just saying it isn’t so won’t do”. Avoiding any answers on just HOW your tax plan will work and NOT hit ordinary folk with bigger tax bills just shows you haven’t got less well-off people’s interests at heart” … and then move quickly on.

But Obama was — in one of the kinder assessments from his supporters — “flat” in dealing with the question. The biggest problem of all, over which Team Obama is doubtless now agonizing, lies in the inescapable reality that you can prep your contender, but it’s a lot harder to inject him with energy.

Obama may have become comfortable, too comfortable, both with power and with his current poll positions. Any bounce the media will give Romney after last night may not be enough to overturn the 4 to 5 percent advantage the president enjoys nationally, or even his slightly lesser lead in the swing, battleground states. But the Democrats cannot safely rely on that.

Both sides have 33 days to go — and two more debates to prep for.