Oil extraction on federal lands and off the coast has quickly become the continental divide of energy policy in this presidential election year. Congressional Democrats have, for the most part, opposed lifting the ban on offshore oil drilling. Republicans, for the most part, support it.

As is usually the case, the issue has more nuance than the rhetoric would suggest. The debate ought to reflect this and the fact that arguments on both sides have merit. A fuller exploration of the potential for increasing domestic oil, with hard and soft costs included and without any presupposed conclusions, ought to be the goal of Congress when it returns from its summer recess.

Reflecting this debate, presidential candidates Sens. John McCain and Barack Obama should be more flexible in their positions on this developing discussion.

Democrats are correct in asserting that drilling now, whether on federal lands, offshore or in the Alaska National Wildlife Refuge, will do nothing to ease $4-per-gallon gasoline and heating oil. If oil companies got leases today for lands and waters now off-limits, oil would not begin flowing for 10 years.

And some people persist in thinking this new supply of oil would somehow be applied exclusively to the U.S. demand. In fact, any oil extracted from, for example, ANWR would be sold on the open, worldwide market, so it would resemble a few drops being added to a big bucket.

Democrats also are correct in arguing that the promise of homegrown oil could distract elected officials from and, more importantly, weaken the public resolve to support alternative fuels, new technologies, public transportation and conservation. The perception of new oil coming from domestic sources could result in a moment of reckoning on the looming end times for the petroleum age passing, yet again, as it did twice in the 1970s.

Republicans are correct in putting drilling on U.S. lands and off the coast on the table for discussion. While a blanket approval for drilling would not be wise, individual areas should be considered. Though any potential impact on market prices is a long time off, the demand may be far greater in 10 or 15 years than it is now. And as a BDN letter writer noted, had President Clinton approved offshore drilling in 1995, oil realized from that effort would be easing prices now.

But the most important role Congress can have in this discussion is to gather facts. Congressional committees are quick to bring oil company executives before them to be chastised about record profits. Those same executives should be grilled by a joint session of the committees of jurisdiction on the real potential for new oil drilling.

If extraction leases were granted for ANWR or offshore, what would be their response? How much would companies invest in exploration? Would there be sufficient financial motivation for more drilling, or would the companies merely sit on the leases and wait for market conditions to change? Would the cost of extraction in ANWR be worth the profit? Is there enough refining capacity?

Congressional questioning would get oil companies on the record on these questions and perhaps point to a needed middle ground on this debate.