The US and its allies are meeting with Iran this week to begin to sketch out the terms of a final deal. The five-day meeting in Vienna, Austria will be the longest since November, and could begin to shed light on potential solutions to some of the most contentious issues still left to decide. Since the implementation of the interim deal in January, Iran has halted the most sensitive aspects of its nuclear program, reduced its stockpile of 20 percent enriched uranium, and shown willingness to compromise on issues such as plutonium output at Iran’s heavy water reactor Arak. These steps combined with positive statements from the European Union’s Catherine Ashton and Iran’s Foreign Minister Javad Zarif has some hopeful that a deal might just around the corner. But with many more issues left to resolve, onlookers should restrain their “irrational exuberance” and not be surprised to see a six month extension of the talks come July. Andrew Szarejko has a rundown of proposals for a final deal here. Some of the most complicated issues include Iran’s ongoing research and development, both on nuclear centrifuges and ballistic missile technology and the duration and timeline of both sanctions relief and ongoing restrictions on Iran. But if and when a deal is struck, there will be heavy lifting ahead back home. The Obama administration will be faced with the task of convincing Congress to roll back sanctions, and hardliners in Iran will oppose almost any deal that is seen as a compromise with the United States. But there are some signs that Congress, at least, is beginning to come around to the idea of a deal. Make no mistake, even the best deal will be a tough sell on Capitol Hill, and some will continue to oppose anything short of Iran’s complete capitulation. (If you need a refresher on why that’s a stupid idea, Colin Kahl does a great job of explaining it here.) But while just a year ago, nearly any vote coming down hard on Iran would have enjoyed substantial majority support in both houses of Congress, a recent vote in the House Armed Services Committee showed a split in U.S. hardliners’ ranks. The amendment to the National Defense Authorization Act (NDAA) offered by Rep. Doug Lamborn (R-CO) expresses a nonbinding “sense of Congress” that sanctions should not be lifted unless the deal includes the complete dismantlement of Iran’s nuclear program and an end to the country’s state sponsorship of terrorism. But such ideas, which once sounded attractive to a less-informed Congress, are now largely understood to be a poison pill. Rep. Adam Smith (D-WA), the ranking Democrat on the committee, spoke out strongly against the amendment. “This is a very bad idea,” said Smith. “It completely ties the hands of our negotiators … by setting out very specific criteria that have to be met before a deal can be achieved, going well beyond the nuclear question.” Such talk would have been political suicide just a year ago, but Democrats have largely coalesced around the President’s position, and they’ve brought some Republicans along with them. Though the amendment ultimately passed by voice vote, the panel was clearly split. With a rising chorus of champions and divisions on Capitol Hill, Congressional sanctions relief, once considered impossible, may now be the best course for enforcement of an eventual deal – as opposed to depending on the Obama administration’s limited (and temporary) ability to waive sanctions.