This week the US House of Representatives overwhelmingly passed legislation limiting Iran's access to refined petroleum by a lopsided vote of 412-12. But while it might be the season to be merry, supporters of stricter sanctions against Iran shouldn't uncork the champagne bottles just yet. The House also passed sanctions legislation last Congress - an even more comprehensive bill sponsored by the late Tom Lantos - but the measure never made it through the Senate, let alone to the president's desk. In fact, recent years have seen many bills, some forward progress, but ultimately failure. The question is whether the new year will finally bring a new law. The bill the House passed Tuesday faces challenges ranging from major differences with the Senate proposal to a list of administration concerns. For starters, where the House bill focuses on keeping foreign companies from supplying refined petroleum products to Iran by denying them access to American markets, the Senate bill includes a wide swath of provisions - on issues as sundry as encouraging state governments to divest from Iran to cracking down on insurance for shipping to and from Iran - that the narrow House measure doesn't touch. Once the Senate passes its bill, the two starkly different pieces of legislation would then have to be reconciled. Though there are different formulas for how the House could incorporate the more expansive Senate language - much of which representatives support - the conference process to sort out those variations could be headache-inducing. And right now the pressing question is when the Senate bill will go through. The Senate is consumed with health care, and numerous important agenda items have been put on hold while that issue makes its way through the body, with the hope that it will get wrapped up this month, before the winter recess. In addition, the Obama administration recently sent a letter to Senate Foreign Relations Committee chairman John Kerry asking for a delay in bringing it to a vote until the beginning of next year, given the current efforts to focus on diplomacy with Teheran and apply any pressure multilaterally rather than by the US alone. "We are entering a critical period of intense diplomacy to impose significant international pressure on Iran. This requires that we keep the focus on Iran. At this juncture, I am concerned that this legislation, in its current form, might weaken rather than strengthen international unity and support for our efforts," wrote Deputy Secretary of State James Steinberg, who added that in addition to the timing issue "we have serious substantive concerns." Those include how much room for maneuver the executive branch would have in exercising the sanctions, as well as "blacklisting that could cause unintended foreign policy consequences"; in other words, that a backlash could mean certain countries that have been cooperating with the US program on Iran would pull back because they feel Congress is unilaterally pushing around their companies. Howard Berman, who replaced Lantos as chairman of the House Foreign Affairs Committee and sponsored the sanctions legislation, indicated his willingness to address some of those concerns when he took to the floor of the House Tuesday to defend his bill, suggesting that these problems could be resolved. "As the administration continues its efforts to pursue stronger multilateral sanctions, I am open to making adjustments to the bill that would make it as effective as possible in meeting that objective, including providing incentives to other nations to join us in supporting a strong multilateral sanctions regime," he acknowledged. "One possibility would be to provide an exemption for companies whose host nations are already enforcing robust sanctions in their national law." IN ADDITION to Berman's flexibility in the interest of getting a bill passed, there are also signs the administration might be more willing to back an approach it has long frowned on - in part because the White House doesn't like Congress dictating foreign policy matters. For one thing, though Steinberg's letter asks for the legislation to be put on hold until the beginning of next year, that's a span of a few weeks, not an eternity. The State Department is pushing for modifications rather than nullifications at this point. And in general, the administration is shifting more toward a stance embracing sanctions rather than focusing almost entirely on diplomacy. In his letter last week, Steinberg notes that "we are engaged in intensive multilateral efforts to develop pressure track measures now" as a strategy for working to keep Iran from building nuclear weapons. This is, indeed, the time that the White House said it would be evaluating its engagement approach on Iran. President Barack Obama told Prime Minister Binyamin Netanyahu as much in their first Oval Office meeting, announcing to reporters afterward that when it comes to engaging with Iran, "we should have a fairly good sense by the end of the year as to whether they are moving in the right direction and whether the parties involved are making progress and that there's a good faith effort to resolve differences." In that context, he said, "we'll probably be able to gauge and do a reassessment by the end of the year of this approach." Now, in one indication of that reassessment, top administration officials like Secretary of State Hillary Clinton and Secretary of Defense Robert Gates have been ratcheting up their rhetoric. On Monday, Clinton pointed out that the Obama administration had been pursuing a "dual-track approach" in which the US had made substantial efforts at engagement. "I don't think anyone can doubt that our outreach has produced very little in terms of any kind of positive response from the Iranians," she said. "The second track of our dual-track strategy is to bring the international community together to stand in a united front against the Iranians and to try to impress upon them the importance of changing their actions and decisions concerning the nuclear program, and certainly additional pressure is going to be called for in order to do that." Administration officials aren't the only ones adjusting their pitch. Berman, speaking to reporters following Tuesday's vote, said he detects greater support for sanctions from all corners. In Congress itself, several progressive members who have expressed reservations about the legislation ended up voting for it. "I rise today disappointed I am here to support the Iran Refined Petroleum Sanctions Act," was how Maryland Democrat Donna Edwards put it. Berman attributed that shift largely to the Iranians. For one thing, their rejection, again and again, of Obama's outstretched hand has made many supporters of engagement more wary and pessimistic of that path. Concurrently, revelations of Iranian duplicity on its nuclear program, particularly the discovery of a secret facility in Qom, have highlighted Iranian misbehavior. And in the meantime, the centrifuges have continued to spin. "The urgency of the situation is so much more clear," Berman said. All of which has combined to make Berman more upbeat than ever that this year it sanctions legislation will finally get turned into law. "I'm more optimistic than I've been since this became an issue," he said. Of course, even if there's a change in the congressional course, and sanctions are passed after years of trying, it still doesn't mean there'll be change where it's most important - in the Iranian regime's behavior.