( CNN ) Fortunately , the intensive diplomatic efforts to prevent a nuclear-armed Iran and another war did n't stop after 47 Republican senators , led by freshman Sen. Tom Cotton , appeared to try to goad Iran 's leaders into forgoing a diplomatic solution to the nuclear dispute . Neither have they stopped since Israeli Prime Minister Benjamin Netanyahu delivered what was effectively a reelection campaign speech on the House floor . Despite so many concerted efforts to sabotage our diplomats , our negotiators are still hard at work to secure an agreement with Tehran that , if successfully concluded , will go down in the annals of diplomatic history as marking a new era for U.S.-Iran relations . Indeed , progress toward a political framework would move us closer to attainable safeguards on Iran 's nuclear program as well as jump-start a more productive relationship that could pay extra dividends for years to come . Before President Obama 's phone call with Iranian President Hassan Rouhani last fall -- the first direct contact between U.S. and Iranian heads of state in more than 30 years -- such an agreement seemed unthinkable . Now , with clear-eyed diplomacy , negotiators from the U.S. and five other countries , plus Iran , are in reach of delivering a peaceful resolution to the decade-long impasse over Iran 's nuclear program . Diplomats have tackled thorny , complex nonproliferation issues that have never been comprehensively addressed in a multilateral agreement before . They have labored to eliminate Iran 's potential pathways to a nuclear weapon while allowing the country to maintain a limited nuclear energy program , but under what is arguably the world 's most locked-down nuclear inspections regime . U.S. , German , British , French , Chinese and Russian negotiators are continuing to build on the solid success of the preliminary nuclear accord negotiated last year , the so-called Joint Plan of Action . That plan continues to grant inspectors daily access to Iran 's nuclear facilities in order to verify its adherence to the agreement . As a result , Iran 's nuclear program will be frozen for the first time since its inception , as diplomats craft a comprehensive resolution to this standoff . If and when a final agreement is reached , the President may temporarily waive some sanctions if Iran 's compliance can be verified . Congress has , for its part , authorized the President to provide limited , temporary and reversible sanctions relief so long as doing so advances U.S. national security interests . As former National Security Adviser Brent Scowcroft and countless other national security experts have attested , such a diplomatic solution to this crisis is squarely in the national interests of the United States . In exchange for Iran following through on its promises to constrain its program in accordance with the agreement , the U.S. Congress will be asked to lift sanctions permanently . If Tehran demonstrates its long-term commitment to limit its nuclear program to exclusively peaceful purposes , then when the time comes , Congress should be ready to lift the sanctions . In the interim , it is crucial that all parties scrupulously adhere to the terms of this landmark agreement . While Iran must not install unauthorized centrifuges , attempt a secret program or otherwise fail to adhere to the agreement , the U.S. Congress also has responsibilities under the agreement , including appropriations for its execution and refraining from imposing new sanctions in violation of either the letter or the spirit of the deal . All this suggests that to jeopardize such progress at this critical stage would be reckless , if not foolhardy . Of course , history suggests that we should be cautious . And the stakes are indeed extremely high . But the last thing the world needs is another major war in the Middle East . Members of Congress should therefore join the preeminent statesmen , military officers and the overwhelming majority of the American public in welcoming what is poised to be a diplomatic success -- one that could protect U.S. security and prevent further instability in the Middle East that would result from a nuclear Iran . We should ensure that our diplomats have the support they need to reach the finish line and that our President is able to cross it .
republican Republican leaders last week signed an open letter to Iran 's leadership . Steve Cohen and senator Wilkerson say Iran relations are at a critical stage .