As an American supporter of Israel, I am strongly against the Iran sanctions legislation recently introduced by U.S. Sens. Robert Menendez, a New Jersey Democrat, and Mark Kirk, an Illinois Republican. I deeply hope that Senate leaders will not move this ill-timed and highly problematic legislation forward.

Supporters of this bill insist that their goal is to prevent Iran from obtaining a nuclear weapon. In truth, this legislation appears to have been deliberately crafted, and its introduction deliberately timed, to kill the promising, still-fragile diplomacy that, as demonstrated in Geneva in November, offers the first real possibility of achieving that goal.

The Geneva interim agreement showed that determined multilateral diplomacy can work. Now is the time to see whether further diplomacy can work, taking us to a final accord that effectively curbs Iran's nuclear program, averting both war and a nuclear-armed Iran.

There may be those, whether in the United States, Israel, or Iran, who for their own reasons would want the current negotiations to fall apart. Some Iranian hardliners would no doubt prefer Iran to remain in permanent conflict with the West and may genuinely see a nuclearized, military path to achieving their wider aspirations. This new bill is a boon to such people: as stated recently in a letter from 10 Senate committee leaders to Senate Majority Leader Harry Reid, D-Nev., “new sanctions only play into the hands of those in Iran who are most eager for negotiations to fail.”

With this legislation, some senators may be sending the message that they, too, prefer diplomacy to fail. The proposed new sanctions violate the terms of the interim Geneva agreement and appear to be devised to incite opposition to further negotiations and any eventual agreement. By insisting that any final agreement include zero uranium enrichment, the bill rejects the internationally embraced formulation of the interim agreement, which could allow Iran low-level enrichment with intense verification for energy generation and medical purposes.

The introduction of this legislation attempts to discredit the coordinated multilateral diplomacy that wrought the interim agreement in Geneva. The ugly battle over the bill in Washington embarrasses and weakens U.S. negotiators and sends a message that the goal of some in the Senate – and some groups lobbying them – is regime change in Iran, not an agreement on Iran’s nuclear program. Such a message undermines the far-reaching international consensus without which sanctions against Iran would not be possible, sanctions that remain firmly in place today. Under the current diplomatic effort, they will remain in place until an agreement is reached – unless overzealous U.S. legislators and activists undermine that diplomacy.

Perhaps most worrisome, this bill sends a message that some people, both inside and outside Washington, may actually prefer war to negotiations, whether initiated by the U.S. or, as alluded to explicitly in the bill, by Israel. Most experts believe military action would guarantee and hasten a nuclear-armed Iran, as Iran’s leader may decide that obtaining a nuclear weapon is an existential requirement to deter future attack. Those supporting war over negotiations may find much in common with Tehran hardliners but little in common with the average American, who has learned that there is no such thing as a short, clean, cost-free war.

There are good reasons to be skeptical about Iranian intentions, skepticism no doubt shared by the P5+1 negotiators (from the U.S., Russia, China, the United Kingdom, Germany and France). However, the unseemly haste with which proponents of this new bill are acting appears based on the idea that if Congress doesn’t pass these new sanctions immediately, it will lose its only chance to act. This is simply dishonest. If diplomacy fails due to Iranian game playing or intransigence, Congress can take action swiftly, while standing on much firmer ground.

What will happen with Iran is of the highest national security importance to the U.S. and the world. Given such stakes, partisanship, politicking, and political pandering should not be allowed to undermine responsible, sober policy. For the sake of all Americans and of America’s interests in the world – including a secure Israel – members of Congress should rally behind President Barack Obama and reject this new sanctions effort.

Mark Silverberg of Moreland Hills is secretary-treasurer and a member of the board of directors of Americans for Peace Now.

This article appeared first in the Cleveland Jewish News on January 23, 2014