If there was ever an issue that required politics to stop at the water’s edge, it’s the fight against ISIS.

With its Mideast land grab, its growing army of Western volunteers, and its global aspirations, ISIS threatens U.S. security interests and must be confronted.

But no one, not the White House, not GOP leaders, certainly not Congress, has come up with a coherent plan to curb the group in the long run.

In a sane government, Congress would debate President Obama’s goals and strategy. The president has said he wanted Congress to authorize his anti-ISIS military campaign once midterm elections were over. A serious congressional debate would press Obama’s national security team to clarify his murky policy and would probe its loopholes. The goal would be to make the country safer, not to rack up political points with an eye to elections in 2016.

Obviously, this is too much to hope for — legislators have shown little appetite for such a challenge. But, as a columnist, I’m free to dream, so here’s how my imaginary hearings would proceed.

First, legislators would admit that the blame for ISIS’s rise is shared equally by Republicans and Democrats. I’ve been critical of Obama’s failure to help moderate Syrian rebel groups two years ago, when such groups still existed, and for failing to pay sufficient attention to Iraq over the past three years. These lapses let ISIS take root.

But no one should forget that George W. Bush’s Iraq war triggered the Sunni-Shiite sectarian struggles that gave birth to ISIS, and guaranteed that Shiite Iran would become Iraq’s most influential ally. This reality should engender a bit of modesty among Republicans — before they call for ground troops to return to Baghdad.

Second, legislators from both parties would seek to clarify the U.S. goals in Syria and Iraq. Obama now says his goals are to “degrade and ultimately destroy” ISIS, while Mitt Romney, bearing the Republican torch, uses the more muscular phrase “destroy and defeat.”

Yet nearly all legislators — whether they are for or against using U.S. troops or in the middle — agree that the bulk of the anti-ISIS fighting must be done by locals. That’s a big problem (see my next point) and doesn’t promise the defeat of ISIS in the foreseeable future. So Congress would do well to listen to testimony from the former ambassador to Iraq, Ryan Crocker, who suggests a more realistic term: “aggressive containment.” In other words, keep ISIS from advancing (Obama’s airstrikes are a good start), while figuring out who will do the fighting on the ground.

Which leads to the third point: the need to examine who can fight ISIS. The hottest issue: whether the United States will return “ground troops” to Iraq, with some Republicans urging this on and many Democrats aghast.

Obama is opposed (along with the bulk of the U.S. public) and says the fighting should be done by Iraqi forces and moderate Syrian rebels. But what exactly are U.S. “ground troops”? There are already 3,000 new U.S. “advisers” in Iraq. The big question is whether some U.S. special forces or intelligence officials should be embedded with forward Kurdish or Iraqi units, to help call in airstrikes and boost local fighters. Even Sen. John McCain, R-Ariz. isn’t calling for the return of U.S. infantry units, and anyway, the Iraqi government doesn’t want them. Hearings could help clarify the U.S. role.

Fourth, a congressional debate could provide a reality check on which Arabs can or will fight ISIS. On the Iraq side, why should we expect better results from retraining the Iraqi army than we got after 10 years of trying? And are our hopes realistic that Iraqi Sunni tribes will rise up against ISIS — especially when Iran, and its Shiite proxies in the Iraqi government, oppose arming those tribes.

As for Syria, is it too late to rely on moderate Syrian rebels to fight ISIS, after letting the Assad regime decimate them over the past three years? The current Obama plan to train 5,000 moderate rebels outside Syria on defensive warfare is useless. It wouldn’t be operative for months, by which time Assad will have decimated the remaining moderates inside the country.

Should we be arming those remaining rebels? Or focusing our help on the Kurds, whom we can rely on to fight ISIS? Hearings could examine.

Joshua Landis, a top Syria expert at the University of Oklahoma, says the only hope is the de facto partition of that country, with Assad (backed by Russia and Iran) agreeing to a cease-fire in the north and east. This rebel zone would be protected by a no-fly zone policed by U.S. and allied air power; Assad would continue to hold the heartland. Then, backed by Turkey, surviving moderates north of the cease-fire line could take on ISIS. Does this idea have potential? Could the United Nations’ talented special emissary for Syria, Staffan de Mistura, help organize the cease-fire?

Abdulaziz Sager, head of a Saudi Arabian think tank, the Gulf Research Center, suggests an Islamic peace force to fight ISIS that would be based in Jordan. Would Jordan — or Iraq — be willing to host them? Or trust them?

Clearly, new ideas on fighting ISIS are needed, beyond Obama’s plans, but they can’t emerge in the take-no-prisoners atmosphere of Washington. “We need a debate to break this ‘either-or’ approach of total war or no war,” says Sen. Bob Casey, D-Pa. It’s a debate, he rightly says, that’s too important to be defined by Republican hostility to Obama.

Is it possible to return to the days when — if it concerned crucial foreign policy issues — partisan politics stopped at the water’s edge? Don’t hold your breath.

Trudy Rubin is a columnist and editorial-board member for the Philadelphia Inquirer.