President Obama told Reuters that the US wants a 10 year freeze on most of Iran's nuclear program:

“If, in fact, Iran is willing to agree to double-digit years of keeping their program where it is right now and, in fact, rolling back elements of it that currently exist ... if we’ve got that, and we’ve got a way of verifying that, there’s no other steps we can take that would give us such assurance that they don’t have a nuclear weapon," he said.

In purely technical terms, it's hard to see how this sort of deal is even possible. The sticking point in the past and now has been how many centrifuges do we allow the Iranians and how efficient can they be.. Iran's enrichment facility at Nantanz is capable of running 50,000 advanced centrifuges. Currently it is believed they have about 12,000 in working condition. But the Iranians have developed a more advanced centrifuge that is far more efficient and could drastically reduce the time it would take to enrich uranium from 5% to thje 85-90% necessary for a nuclear weapon.

Keeping the old style centrifuges in place would be nice, but its hard to see how the Iranians could possibly agree. In fact, they've already rejected the idea of a long term freeze on their program:

Iran on Tuesday rejected as "unacceptable" U.S. President Barack Obama's demand that it freeze sensitive nuclear activities for at least 10 years, but said it would continue talks aimed at securing a deal, Iran's semi-official Fars news agency reported.

"Iran will not accept excessive and illogical demands," Iranian Foreign Minister Mohammad Javad Zarif was quoted as saying by Fars.

"Obama’s stance ... is expressed in unacceptable and threatening phrases ... ," he reportedly said, adding that negotiations underway in Switzerland would nonetheless carry on.

Zarif and U.S. Secretary of State John Kerry sat down for a second day of meetings hours after Obama had told Reuters that Iran must commit to a verifiable halt of at least 10 years on sensitive nuclear work for a landmark atomic deal to be reached.

The aim of the negotiations is to persuade Iran to restrain its nuclear program in exchange for relief from sanctions that have crippled the oil exporter's economy.

The United States and some of its allies, notably Israel, suspect Iran of using its civil nuclear program as a cover to develop a nuclear weapons capability. Iran denies this, saying it is for peaceful purposes such as generating electricity.

Kerry and Zarif met in the Swiss lakeside town of Montreux as Israeli Prime Minister Benjamin Netanyahu prepared to criticize the diplomacy in a speech to Congress in Washington.

Despite the tough tone of Zarif's remarks quoted by Fars, the Iranian struck a more conciliatory tone when he spoke briefly to reporters after about two hours of talks with Kerry.

Asked if the two sides had reached an agreement, Zarif replied: "We'll try, that's why we are here."

Other technical sticking points include the IAEA verification regime. Iran has continously rejected the kind of verification program that would instill confidence in the west that they are not building a bomb. In fact, they have violated the interim agreement by failing to be forthcoming on their activities related to a nuclear weapons program.

The president recognizes the problems and sounds skeptical that a deal can be reached:

Despite recent progress in the talks, Obama suggested there had been little change in his assessment that the negotiations have less than a 50 percent chance of success.

"I would say that it is probably still more likely than not that Iran doesn’t get to 'yes,' but I think that, in fairness to them, they have been serious negotiators and they’ve got their own politics inside of Iran. It is more likely that we could get a deal now than perhaps three or five months ago," he said.

There is still a long way to go to June 30 when a deal is supposed to be completed. But given the "progress" of the talks to date, it is likely that not only will that date slip, but the one at the end of March that requires the two sides to have negotiated a "framework" for a deal will also be moved. Will Netanyahu's speech alter the dynamic of this debate? That isn't likely. The Democrats are making their stand with Obama and any hope for a bi-partisan sanctions bill is gone. But Bibi's talk, if nothing else, will put some spine into the deal's opponents and encourage continued opposition.