Everything You Need to Know About the Iran Nuclear Talks

— -- After a second extension in November, the Iran nuclear talks are back on.

Secretary of State John Kerry met with his Iranian counterpart, Foreign Minister Mohammad Javad Zarif, twice this week in Geneva and Paris, and staff-level talks have resumed under a March 1 deadline.

At a press conference on Friday, President Obama sought to convey the negotiations’ importance alongside UK Prime Minister David Cameron, a close partner among the countries negotiating with Iran, which have been dubbed the P5+1: the five permanent members of the UN Security Council—the U.S., UK, Russia, China, and France—plus Germany.

“I've always said that the chances that we can actually get a diplomatic deal are probably less than 50-50. Iran is a regime that, you know, is deeply suspicious of the West, deeply suspicious of us,” Obama said. “We have huge differences with them on a whole range of issues.”

Cameron, for his part, acknowledged that he’s personally lobbied U.S. senators against passing new sanctions that could sink the talks, while Obama promised a veto if Congress makes that move.

With neither side commenting publicly on the substance of the talks, many questions remain unanswered. Here are some critical things to keep in mind.

ROUHANI WANTS A VOTE

Last week, President Hassan Rouhani caused a stir in Iran by calling for a public vote.

Addressing an economic conference, Rouhani suggested holding referenda on issues of significant national concern, state news agency IRNA reported, proposing to implement a little-used provision in Iran’s constitution that allows for such referenda. Many interpreted that as a reference to the nuclear talks.

Experts say such a vote is very unlikely, but they see in Rouhani’s comments a bold move to confront hardliners—and a sign that Rouhani believes Iran’s public wants a deal.

“Rouhani calculates that the population in the country is so aware of this, is so closely following, that they would side with him,” says Trita Parsi, author of multiple books on Iran and the West’s diplomacy with it.

In Iran’s political system, the president controls parts of the government but has to contend with other factions, while the supreme leader, Ayatollah Ali Khamenei, is the most powerful person in the country. Rouhani has pushed for more global engagement, having won office in a 2013 whose results were widely seen as legitimate, according to experts.

“He knows his powers are contained or limited. What he has is popular support, because people voted for him, so he can always threaten to use that popular support if he sees an obstacle coming,” says Alireza Nader, an Iran expert at the RAND Corporation. “I think he does see an obstacle coming.”

WHAT THE SIDES ARE TALKING ABOUT

The very broad outline of a deal was laid out more than a year ago.

Iran and the P5+1 are negotiating under an initial framework that calls for “comprehensiv[e]” lifting of nuclear sanctions against Iran, “including steps on access in areas of trade, technology, finance, and energy, on a schedule to be agreed upon.”

That would include U.N. sanctions, the multilateral sanctions engineered by the U.S. under Obama, and the U.S.’s own unilateral sanctions. Other U.S. and international sanctions, such as those in place over Iran’s human-rights record, would remain.

In exchange, Iran would agree to a “mutually defined enrichment program with mutually agreed parameters” and “agreed limits on scope and level of enrichment activities.” Iran has already downgraded some of its uranium stockpile, moving further away from a bomb, but observers expect a final deal would include more rollbacks on enrichment capabilities.

Iran would also fall in line with international monitoring under the International Atomic Energy Agency and address concerns over its heavy-water reactor at Arak, which could supply a different scientific path to a nuclear weapon.

The talks have included “technical experts” on both nuclear science and the logistics of rolling back sanctions.

WHAT THE POLLS SAYIn the U.S. and Iran, polling generally points toward public support for a nuclear deal, with some major caveats.

In late 2013, an ABC News/Washington Post survey found 64 percent of U.S. respondents supported a deal. Oddly enough, most (61 percent) weren’t confident such a deal would actually prevent Iran from getting a nuclear weapon.

Among those who had no confidence a deal would work, 38 percent still wanted one, and 80 percent of other respondents wanted a deal, including those “not so” confident one would actually work.

At the same time, Americans appear deeply skeptical of Iran. In February, Gallup found that Iran carried an 84 percent unfavorable opinion rating in the U.S. and that 76 percent viewed Iranian nuclear weapons as a “critical threat” to U.S. interests. In 2012, more Americans (36 percent) said Iran was America’s number-one enemy than any other nation, but it’s now tied for second with North Korea (at 16 percent), with China in the top spot.

Polling of Iranians should carry some doubts, given speech restrictions there, but in October 2013 Gallup found Iranians generally opposed to developing nuclear weapons (41 percent against, to 34 percent for, with 25 percent having no opinion or declining to comment). A full 85 percent said sanctions U.S., UN, and multilateral sanctions were hurting their personal livelihoods to some degree, and in 2012 67 percent of Iranians disapproved of U.S. leadership—the worst rating among Iranians for any of the P5+1.

WHAT ABOUT CONGRESS?Many lawmakers are wary of the talks, and Congress might be able to sink them.

Skeptics have warned against trusting Iran, and some want to pass a new sanctions bill now—a move that could end the talks and scuttle any deal in the making.

Sen. Robert Menendez, D-N.J., has led the way along with Republican Sen. Mark Kirk, Ill., to push a bill that would trigger new sanctions if the talks fail, or if Iran doesn’t meet its obligations, arguing their bill would safeguard against Iran duping U.S. and world negotiators.

The initial agreement bars any new sanctions while the talks are ongoing, and in Iran’s stated view, passing a bill now would violate it. President Obama said Friday he would veto such a bill.

Kirk and Menendez, a senior member of Obama’s own party, nearly reached a veto-proof majority for their plan in the last Congress, gaining 59 cospsonsors with bipartisan support. The new GOP majority means a Senate even more hostile to Obama on a broad range of issues, though it’s not certain that more Republicans would mean more votes for sanctions.

More importantly, Obama would likely need congressional buy-in down the road. In order to “lift” the sanctions under a final deal, Congress would almost certainly have to alter U.S. laws that compel the president to enforce sanctions against Iran.

The key here is timing. The administration says that while Congress will play a role, it can use executive authority to “suspend” rather than “lift” some sanctions at first, until Iran proved over time that it had met its obligations.

“We would look to suspend sanctions,” State Dept. spokeswoman Marie Harf said in October. “And then, only if and after Iran has upheld its end of the agreement, would we look to lift or terminate sanctions.”

Congress may want to have its say on the front end, wary of negotiators promising that Congress would vote a certain way in the future. Senate Foreign Relations Chairman Bob Corker, R-Tenn., a leading GOP voice on the issue, proposed legislation last year requiring a vote in Congress before any deal could go through.

WHAT THE IRAN-WATCHERS SAYIran experts in the U.S. have mixed views on what will happen.

Suzanne Maloney of the Brookings Institution talks of “if and when this whole thing goes down in flames” and says no one she talks to is optimistic.

“The most likely scenario is some beefed-up version of the interim accord,” Maloney told ABC. Political elements in Iran could accept nuclear constraints but would likely resist doing away with centrifuges Iran already has, she says.

“If the centrifuge number remains as is, I think it would be inconceivable to come up with a formula that’s sufficient to convincing the U.S., the French, the British,” Maloney said.

Others are more sanguine.

Parsi sees the two sides at least moving closer together. “As the two sides are getting closer to a deal, you’re going to see opposition to a deal in Washington and Tehran,” he said. “Obama and Rouhani [will] become a little more forward leaning in pushing for their deal at home.” Parsi said Obama has already done this, using more optimistic language about getting something done.

Nader sees Rouhani’s referendum talk as a sign of potential movement, a sign that Rouhani is trying to “prepare” his domestic audience for a potential agreement.

“Overall, I’m optimistic that there could be a deal,” he says.

This story has been updated. Alireza Nader was inaccurately cited as being affiliated with the Council on Foreign Relations. He is an Iran expert at the RAND Corporation.