Here’s the bottom line on the Iran nuclear pact: Whether you like it or hate it, or feel as I do — that it’s barely passable, but U.S. negotiators could have done better — it’s a done deal.

There are many things in this pact that make me queasy. And the administration’s Iran-empowering policy gives me heartburn. But if this deal goes down to defeat (with Congress overriding a presidential veto), international sanctions will collapse and Iran will be free to ramp up its nuclear program now — rather than in 10 to 15 years. Political pressure will inevitably rise for a military strike, which would be counterproductive.

This means the least-bad option is to try to make this deal work.

So legislators who care about U.S. and Israeli security (as opposed to cheap campaign posturing) should be looking for ways to bolster the accord and offset its weak points. Here are a few suggestions on how Congress could make productive use of its 60-day review:

One. Stop pretending there was/is a way to end Iran’s nuclear program via sanctions or war. The geopolitical realities that circumscribed the talks date to the 2003 Iraq invasion. Most experts agree that the U.S.-led invasion of Iraq and the dismantling of its armed forces left Iran as the leading regional power in the Gulf region.

An empowered Iran has made clear it will not dismantle its entire nuclear enterprise, no matter how harsh the sanctions. Even a military strike would have set Tehran’s program back only two to five years, depending on whether the United States joined Israel. That would enmesh us in another unpredictable Middle East conflict. Does anyone really think that’s a good idea?

Two. Take an honest look at the deal’s good points, because they are what need strengthening. The deal slashes the number of functioning Iranian centrifuges for 10 years and shrinks its large stockpile of enriched uranium to a minimal amount for 15 years.

Iran’s plutonium route to a bomb is blocked for at least 15 years. Even most skeptics believe that, with continuous monitoring provisions in place for known facilities, Iran’s path to “break-out” (production of one bomb’s worth of fissile materiel) will be circumscribed for more than a decade. One might have hoped for a longer breather, but this is still an achievement.

Three. Press the administration on verification measures, with an eye toward ensuring that the 10- to 15-year breather actually materializes. Here is where congressional pressure is key.

At present there are far too many loopholes for comfort in the provisions for preventing Iran from cheating. Congress should press the administration for details on how it will address them. To mention a few: Are the numbers and equipment of International Atomic Energy Agency sufficient for their enormous task? Could IAEA inspectors really discern signs of Iranian cheating at secret sites — as administration officials insist — since Tehran can delay surprise inspections for up to 24 days?

What is the U.S. plan for maneuvering through the complex procedures required to “snap back” sanctions if Iran is caught cheating, especially if the ayatollahs cheat in small steps? Will European allies agree to “snap back” if their companies have already signed contracts? Does Iran have the right, as some interpret the deal, to exit the deal if the allies “snap back” the sanctions?

Congress should demand assurances that the administration is committed to respond if Iran is found cheating and that there will be the closest cooperation between U.S. and Israeli intelligence agencies. These questions and many more must be clarified.

Four. Demand that the White House spell out its plans to counter Iranian mischief in the Middle East. The deal aimed only to curb Iran’s nuclear program, but it will also enhance Tehran’s regional stature and its finances. Iran is already stirring up sectarian strife in Iraq, Syria, Lebanon, and Yemen, strife that drives Sunnis into the arms of ISIS.

Legislators should press the White House to be more forthcoming on plans to reassure its Mideast allies that it will offset future Iranian misbehavior. The White House needs to remove its rose-tinted glasses about a possible transformation in Tehran.

President Obama needs to rethink his policy toward an emboldened Iran.

Needless to say, there are many other points about which the Senate and House need clarification. I will write about more of them in coming weeks.

But before consigning the Iran deal to the rubbish heap, its congressional critics need to spell out their alternative vision for curbing Iran’s nuclear program. If there’s a better alternative than working to strengthen the Vienna accord, I’ve yet to hear it. And I haven’t seen anyone present one on Capitol Hill.

Trudy Rubin is a columnist for the Philadelphia Inquirer.