Elections generate laundry lists of variables, making it difficult to determine specifically why somebody wins. Yet when one candidate outspends his rival by nearly four-to-one in TV advertising, well, suddenly television networks have more of a dog in this fight than usual.

Armed with an unprecedented $600 million war chest, Barack Obama is flooding the zone with ads in the presidential campaign’s home stretch, including a half-hour primetime political infomercial Oct. 29 that will air on multiple networks. Without putting too fine a point on it, if that aerial assault doesn’t help the Democratic nominee close the deal, it would seem to be bad news for network sales operations, which have long clung to the pitch that their medium — beleaguered and battered as it is — remains the best marketing tool ever devised.

Admittedly, all kinds of factors are shaping the current race, but many relate to the question of the 30-second TV spot’s enduring value. Obama’s team, for example, is relying on younger voters to turn out in droves — a demographic slice (basically, age 18-29) that has been as elusive to television programmers lately as they have to previous campaigns. (Notably, the Democrat’s arsenal includes first-ever presidential ads within Electronic Arts videogames — among them the popular “Madden ’09” — one of the new conduits to which young men especially have defected.)

As Evan Tracey of TNS Media Intelligence/CMAG told the Wall Street Journal, “[John] McCain is in a shouting match with a man with a megaphone.”

Of course, voters could reject McCain and embrace Obama — or vice versa — for a variety of reasons that have nothing to do with who produces the best and most ubiquitous ads. Obama, moreover, possesses what’s widely considered a superior “ground game” in key states, while McCain has the weight of an unpopular Republican president tethered to his ankles.

Even so, the deflating message for television if Obama loses will be that his advertising avalanche didn’t yield the intended result — raising new red flags about TV’s ability to move a product, diluted as it is by digital video recorders, ad-skipping and overall fragmentation.

As colorfully laid out on the Television Bureau of Advertising’s website, TV has long boasted that its ads are perceived to be “the most ‘influential,’ ‘authoritative,’ ‘exciting,’ and ‘persuasive.'” Despite the online insurgency, TVB also notes that adults “spend significantly more time with television” than other media, with viewing levels in 2007 — more than eight hours daily per household, and roughly five hours for individual adults — virtually unchanged compared to 2003.

Oh, and one more footnote: Obama fares best in polls among college-educated voters, who as a group watch considerably less television than those lacking a degree. That means his commercials are disproportionately reaching the skeptical audience that he needs to win over.

Obama’s TV blitzkrieg must be inordinately galling to McCain, who alienated many within his own party by championing the McCain-Feingold bill, a campaign finance-reform measure that sought to mitigate money’s corrupting influence over politics.

The Journal’s conservative editorial board — which liked the idea of buying elections far better when their guys did the buying — recently whined about Obama’s advantage, bitterly observing that McCain is “being outspent — and should the polls hold, beaten — thanks in part to the laws he worked tirelessly to put on the books.” For his part, McCain cited the Democratic spending spree on Fox News Channel and warned that pouring huge amounts of money into the political game “always leads to scandal.”

Indeed, one inevitable side effect of an Obama victory would be further escalation in the fundraising wars, as campaigns seek to control their message through advertising, a tactic that theoretically gains weight as substantive news coverage (most conspicuously in local markets) continues to evaporate.

As the saying goes, nothing sinks a flawed product faster than effective advertising. Just ask the Big Three U.S. auto makers. Still, Americans have had two years to kick the tires and appraise Obama, and he’s betting a sizable portion of $600 million that saturating TV can inspire them to buy.

If for some reason they don’t, accusing fingers will surely point in all directions — but one of them will be poked directly into TV’s eye.