Lately it's been the latter. During his acceptance speech at the Republican convention, Mitt Romney faulted President Barack Obama because "gasoline prices have doubled" on his watch, while lamenting the plight of a hard-pressed American "watching the gas pump hit $50." Message: You won't have to do that when I'm president.
His line of attack sounds curiously similar to the complaints of Democrats when the last Republican was in office. In 2008, Rep. Debbie Wasserman Schultz of Florida upbraided oil company executives, "I'm a mom of three young children who filled up her minivan the other day for $68. Sixty-eight dollars -- that's real money."
Democrats led us to believe they would do better. But Wasserman Shultz, now head of the Democratic National Committee, is just one of many in her party who have been oddly quiet on the subject lately.
The posturing by partisan leaders may look hypocritical, and it is. But it also exposes something even more important: how little the conscious decisions of our elected officials affect this issue they invest with such importance. In this area, they are loath to admit that they are often unimportant and sometimes completely irrelevant.
That has never been more obvious than in the past few years. Democrats assailed President George W. Bush and the oil industry when pump prices soared above $4 a gallon four years ago. Obama was so aggrieved he called for a windfall profits tax to punish oil companies for "price-gouging." Republicans, meanwhile, blamed Democrats for opposing an expansion of oil drilling.
But then, before Obama could even take office, a funny thing happened: Prices plunged off a cliff, bottoming out at a now-incredible national average of $1.69 a gallon. Something else funny happened: No one celebrated or rushed to take credit.
Why not? Because it wasn't energy policy that caused the reduction. It was a recession, compounded by a financial panic. You want to cut gas prices? There's no medicine like an economic collapse.
It was not the cure Republicans had in mind. Remember the chant that erupted repeatedly at their 2008 convention? "Drill, baby, drill!" If we did, Sarah Palin and others assured us, the resulting gusher would slash driving costs.
At this year's convention, the chant had fallen out of fashion. Maybe that's because it might lead voters to realize something the GOP would prefer not to publicize: Under Obama, domestic oil output has sharply increased, and prices have gone up anyway.
In recent months, U.S. fields have been churning out more than 6 million barrels of crude per day -- the highest level since 1998. The number of drilling rigs in operation has more than tripled. If you didn't know better, you'd think a Texas oilman was in the Oval Office.
But the apparent glut has not brought down retail prices. This is not entirely bad news. As the economy has grown, albeit slowly, demand for energy has grown as well. If economic growth had been more vigorous, in fact, prices would be even higher than they are now.
Obama thus finds himself cursed with painful driving costs even though the usual important factors should have kept them down. Until recently, strong growth in places like China and India fed high worldwide demand. The possibility of an attack on Iran has created fears of a supply disruption. Hurricane Isaac and refinery problems have tightened the squeeze.
All of this highlights the banal reality: There's not much this or any other president can do to manage today's unpredictable worldwide market to please American consumers. Events beyond our borders can overwhelm the effects of U.S. government policy.
So when politicians talk about gas prices, don't pay much attention. Knowing which candidate will win the presidential election wouldn't tell you much about what you'll be paying at the pump over the next four years.
When it comes to the oil market, the next president is likely to find himself in the same position as an illustrious predecessor. "I claim not to have controlled events," said Abraham Lincoln, "but confess plainly that events have controlled me."