American schoolchildren weren't the only ones donning their new clothes and sharpening their pencils this week. Members of Congress returned from their summer recess Tuesday and got back behind their desks on Capitol Hill. While health care and financial reforms have been at the top of the agenda, many Jewish groups are focusing on Iran sanctions legislation, which was introduced this spring but has been dormant until now. Hundreds of Jewish activists organized an Iran advocacy day Thursday, viewing the weeks leading up to the Obama administration's deadline for Iran to accept its offer of engagement as a crucial mobilization period for finally getting enhanced sanctions legislation through Congress. House Foreign Affairs Committee chairman Howard Berman explained at a hearing in July that when he introduced his Iran sanctions bill in May, "I said that I did not intend to immediately move it through the legislative process. I wanted - and still want - to give the administration's efforts to engage Iran every possible chance to succeed, within a reasonable time frame." At the hearing he backed President Barack Obama's time frame of the G-20 meeting of industrialized nations on September 24, coinciding with the annual opening of the UN General Assembly, for evaluating Iran's response. He then continued, "If engagement doesn't work, then I am prepared to mark up the bill in committee early this fall." Meanwhile, similar legislation on the Senate side sponsored by Democrat Evan Bayh, Independent Joe Lieberman and Republican Jon Kyl has already been referred to the Banking Committee, with a hearing and potentially other actions in the works over the coming weeks. "I would not be surprised if there's continuing momentum between now and the G-20 and UN General Assembly, but the trigger doesn't get pulled until after that deadline," said one Senate aide familiar with the legislation. The Obama administration has talked about the importance of sincere engagement with Iran, but has also warned of "crippling sanctions" should engagement fail. Sponsors see this legislation as putting substance behind the rhetoric. Though Congress has attempted to expand existing Iran sanctions legislation repeatedly in recent years, it hasn't been successful in getting to the finish line. As in years past, the current House and Senate bills have the bipartisan support of more than half of the two chambers, and now could be getting a boost from the very forces - events on the ground - that have so far held them up. While the focus had been on giving Obama's outreach strategy time to work, the fiasco of Iran's presidential election and crackdown on dissidents, coupled with IAEA noncompliance and a lack of responsiveness to the US offer of diplomatic talks, have raised serious questions on the American side about the efficacy of engagement. "Certainly the perception now is that it seems even less plausible than it did even a few months or weeks ago that the Iranians are prepared to have a serious conversation," said the Senate aide. "If things continue on the current trajectory, where you have an administration that's looking increasingly at sanctions and other punitive measures you can take against Iran to change their calculus, the prospects of the bill moving forward increase." But he pointed out that a lot depends on what Iran does next - as well as the US administration. For now, the administration's holding its cards close to its vest. The White House declined to respond to questions about whether it supported or opposed the sanctions bills, and several observers have pointed out that while various administration officials have referred to "crippling sanctions," few have spelled out what exactly they would consist of. Previous administrations have been leery of sanctions legislation because they generally saw them as usurping the executive branch's supremacy in determining foreign policy, though they were often glad to use the threat of the legislation to cajole international partners - whose companies would be affected by the sanctions - to take steps in concert with the US. That way the US can tell European and Asian countries, "It's not us, but if we don't start showing some results, Congress will come down hard," in the words of Michael Jacobson of the Washington Institute for Near East Policy. "I would guess this administration would want it as a tool, at least in part, for the same reason." At the same time, he expected the Obama administration would be wary of sanctions legislation antagonizing the same countries it's trying to get on board in a multilateral framework. American companies are already barred from dealing with Iran by legislation passed in the 1990s, so the new bills would largely affect European and Asian businesses. "The question is going to be how do you move forward with this and use it as leverage rather than create a backlash?" Jacobson asked. "It won't be simple." Those difficulties, administration reservations and various political shenanigans have doomed sanctions efforts in the past, notably in the last Congress where much more comprehensive legislation had been proposed early in the term to no avail. This legislation takes a much more narrow approach, giving the president the ability to sanction companies that sell refined petroleum to Iran as well as those who insure them. Bill advocates say it focuses on an Iranian sector that is particularly vulnerable and where sanctions could be particularly effective, though the Senate aide who spoke to The Jerusalem Post, said the Senate version might soon be expanded to include elements found in bills from earlier terms. Whatever form emerges, he said that if Iran continues with its intransigence on the nuclear issue, knocking out the engagement option, he expects to see success where previous efforts failed. He pointed out that either the administration would become a driving force for some measures against Teheran, or Congress would take matters into its own hands. "It's going to be very hard after the deadline if nothing has happened for the administration to say, 'Do nothing, just give us more time,'" he said.