With only one day left to seal nuclear talks between the P5+1 and Iran, a senior US official told media on Sunday that negotiations will mostly likely be extended past their June 30 deadline.

Iranian Foreign Minister Mohammed Javad Zarif flew back to Iran Sunday to consult with officials in his country before signing an official deal, Iranian media reported. Leaving so close to Tuesday’s deadline leaves many wondering how much more needs to be negotiated that Zarif must fly back to Iran for instruction.

Former CIA Director Michael Hayden told Fox News Sunday that the US has lost its edge in the final home stretch of nuclear talks. “I would actually fear that the Iranians have the upper hand right now,” he stated. “I actually fear we have painted ourselves into a corner where we believe that any deal is better than no deal at the present time.”

Among the details still being discussed is US insistence of more intrusive monitoring of Iran’s nuclear program, which Iranian officials have refused. Iranian Gen. Masoud Jazayeri warned that any inspections by foreigners of Iranian military facilities is expressly forbidden.

He accused the US and its western allies to attempting to “obtain Iran’s military information for years…by the pressure of sanctions.”

World powers could not confirm how many days or even months negotiations would need to be extended in order to come to an agreement. Zarif told reporters who intended to return to Vienna on Tuesday in order to close the deal.

“Given the dates, and that we have some work to do…the parties are planning to remain in Vienna beyond June 30 to continue working,” a State Department official, on condition of anonymity, told reporters.

Frederica Mogherini, the European Union’s chief diplomat, said chances of a closing a deal are “going to be tough…but not impossible.”

Weighing in on the direction nuclear negotiations are now headed, Israeli Prime Minister Benjamin Netanyahu said the US must make tougher demands on the Islamic Republic. A staunch and vocal opponent of the talks, the prime minister said “this bad agreement…is becoming worse by the day.”

“It is still not too late to go back and insist on demands that will genuinely deny Iran the ability to arm itself with nuclear weapons,” he warned.