P5+1 negotiators are in the final home stretch in nailing down a framework agreement with Iran on its nuclear program.

Aiming to stop Iran from acquiring a nuclear weapon, Tuesday is the last day both sides have to come to an arrangement that would set in motion the next round of talks.

Officials say progress has been made but key differences remain. US Secretary of State John Kerry, who is leading a team of negotiators from the US, United Kingdom, France, Britain, China, Russia and Germany, said that despite the latest meetings with his Iranian counterpart, Mohammad Javad Zarif, there “still remain some difficult issues.”

“We are working very hard to work those through. We are working late into the night and obviously into tomorrow,” Kerry told CNN on Monday.

As of Tuesday afternoon, recent updates indicate that negotiators will seek to extend the latest round of talks into June in what is being hailed as a new phase of negotiations, the Associated Press reported.

The US has made clear that Iran’s failure to compromise on a nuclear agreement would rule out any further nuclear talks and lead to an increase of harsher sanctions on the Islamic Republic.

Acting State Department spokeswoman Marie Harf said on Monday it was up to the Iranians on whether the nuclear deal would come to fruition. “It’s sort of time to see whether they can make these decisions,” she said.

Flaming rumors that a deal may ultimately not be reached, Russian Foreign Minister Sergey Lavrov returned to Russia and is said to only consider returning to Switzerland is there is a “realistic” chance of a deal, his spokesman confirmed.

According to details of the deal, Western powers are calling on Iran to scale back its nuclear program in various ways to extend the “breakout” time the country would have in acquiring a nuclear bomb.

One of the main points of contention between negotiators is the future access Iran would have in enriching uranium. According to initial reports, the US is said to be allowing Iran to run 6,000 centrifuges, some of them in a fortified, underground nuclear site.

Iran has repeatedly denied it seeks to acquire nuclear weapons and has demanded the West lift all sanctions, which have choked off its economy.

Other issues include access by International Atomic Energy Agency (IAEA) inspectors to all Iranian nuclear sites for at least the next decade.

Should a deal not be reached by midnight, Harf explained that the Obama administration is “planning for contingencies.”

“We will have to take a very hard look at where we are and we will have to decide what happens next,” she stated. “No one is thinking about what will happen if there is no deal. No one has discussed this in the talks. Everyone is focused on finding solutions.”

As the fate of nuclear negotiations will be determined by midnight, a new Washington Post-ABC News poll found that almost two-thirds of Americans support easing economic sanctions on Iran in exchange for certain restrictions.

However, majority of respondents (59 percent) said that they do not believe a deal will prevent Iran from acquiring nuclear weapons.

When asked if they would support a deal that would lift sanctions in exchange for making it harder for Iran to produce a nuclear weapon, 59 percent of respondents backed the deal while 31 percent said they would oppose it.

Meanwhile in Israel, Prime Minister Benjamin Netanyahu warned on Monday that any agreement with Iran would be seen as rewarding the country’s “aggression” in Yemen.

“The agreement being formulated… sends a message that there is no price for aggression and, on the contrary, that Iran’s aggression is to be rewarded,” he stated. “The moderate and responsible countries in the region, especially Israel and also many other countries, will be the first to be hurt by this agreement.”

“One cannot understand that when forces supported by Iran continue to conquer more ground in Yemen, in Lausanne they are closing their eyes to this aggression,” Netanyahu said. “But we are not closing our eyes and we will continue to act against every threat in every generation, certainly in this generation.”

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