There’s cause for gloom as Congress and the president boot the hard decisions in their debt-ceiling-and-deficits deal to a so-called “supercommittee” of 12 House and Senate members. But there’s also the potential for genuine euphoria. This deal hands the dozen committee members unprecedented clout to cut the grandest of grand deals. These 12 lawmakers have the power — if they’ll seize it — to reform spending and taxes far more ambitiously than anyone now expects of them. The power, that is, to rescue their government from the debt that could well strangle it.

Think creatively and you’ll see why this group — three members from each party in each house of Congress — hold astonishing opportunity in their hands. They can negotiate what the full House, Senate and White House have proved they cannot. Consider:

Even with the threat of credit downgrade hanging over them, the congressional leaders and administration officials who negotiated this deal couldn’t stop federal debt from continuing to grow by the trillions. Many Democrats lack the political courage to slash entitlement spending. Many Republicans lack the political courage to raise revenues. Noble positions both, perhaps, but indefensible when the government is pointed toward insolvency and then bankruptcy.

We’re glad official Washington staved off default and for once linked a debt ceiling increase to real deficit reductions. But we can’t disagree with Robert Bixby, executive director of the Concord Coalition, a group dedicated to responsible public finances: “Once again, (political leaders) are leading with discretionary spending cuts while leaving the biggest problems — entitlement and tax reform — for another day. . . . The fundamental fiscal crisis is pretty much unchanged.”

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The bill President Barack Obama signed into law Tuesday calls for deficit reductions of nearly $1 trillion over 10 years. The joint House-Senate committee — members to be named later — has until Nov. 23 to propose another $1.2 trillion to $1.5 trillion in additional cuts and/or revenue hikes. A committee deadlock supposedly would trigger automatic spending cuts neither party wants.

But here’s where big opportunity unfolds: If at least seven members of this supercommittee can craft an agreement, Congress has until Dec. 23 to vote that plan up or down, with no amendments or Senate filibusters. And if we’re reading correctly, nothing limits the committee to $1.5 trillion in spending cuts or tax hikes.

Its members instead can reach for a megabargain: many more trillions in long-range spending cuts to entitlements, defense and other programs, offset in part by trillions in long-range tax reforms, starting with an end to many deductions and loopholes. We’ve argued for a cuts-to-revenues ratio of 3- or 4-to-1; Congress got to where it is by overspending and overpromising.

Imagine the realpolitik if the supercommittee cuts that grand a deal and confronts an aghast Congress with a package it has to vote up or down. The committee could bulwark its plan with some inconvenient facts:

Federal spending has exploded to one-quarter of our gross domestic product. Federal debt held by the public also has exploded, from 40 percent of GDP three years ago to perhaps 72 percent this year. Government efforts to spend our way to renewed growth, including job creation, just haven’t worked. We’re courting another recession, our unemployment rate remains intolerable and Washington’s inability to settle once and for all on spending and taxes has employers terrified to add workers for fear of what comes next. What’s more, it’s not just Republicans who don’t want to raise taxes: Democrats didn’t raise them when they controlled both houses, and Senate Majority Leader Harry Reid didn’t dare ask his majority to vote for higher taxation in his own debt ceiling plan. Obama, too, dropped his once nonnegotiable demand for tax hikes in the final deal.

A much bigger fix, though, would — after they grump and groan and posture for the cameras — give members of both parties a fabulous opportunity to claim victory. Democrats could boast of securing tax increases to save entitlement programs otherwise doomed to implode as baby boomers age. Republicans could boast of tightening those runaway entitlements and of taming the nation’s gargantuan debt.

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Just this sort of we’re-all-in-this-together reasoning, coupled with up-or-down votes on a commission’s recommendations, enabled Congress to set aside parochial concerns and approve the closing of some of our surplus military bases.

We doubt that the Washington leaders who created this bicameral supercommittee envisioned it as a source of some omnibus solution. They were staring at a possible default deadline and wanted to delay some difficult decisions that they couldn’t make themselves.

We hope, though, that the supercommittee members see the larger possibility here. The four caucus leaders of Congress soon will chose those 12 members. In the best of all worlds, the leaders will pick big thinkers rather than reliable obstructionists who wouldn’t dream of wavering from party orthodoxies.

Without an agreement on spending and revenues that is much more ambitious than what Obama has signed into law, Americans will spend years fighting over the size and scope of government, spending and borrowing. Our rising debt load guarantees that.

Intended or no, the supercommittee that now will convene has a platinum opportunity to rescue all of us — and this nation’s financial future — from that grim fate. Then Americans can get back to growing an anxious economy that craves what Washington hasn’t supplied: stability.