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. But if this deal goes down to defeat, 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:

One. Stop pretending there was/is a way to end Iran’s nuclear program via sanctions or war. As two experts on Iran’s nuclear activities, Shai Feldman and Ariel Levite, wrote recently: “The U.S.-led invasion of Iraq and the complete dismantlement of its armed forces left Iran as the uncontested regional power in the Persian Gulf.”

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.

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.

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. Has the White House thought this through? These questions and many more must be clarified.

Tehran hasn’t let the talks affect its negative actions in the region. So the White House needs to remove its rose-tinted glasses about a possible transformation in Tehran.

Needless to say, there are many other points about which the Senate and House need clarification.

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, I’ve yet to hear it.