While U.S. negotiators made progress Wednesday in their efforts to reach a nuclear deal with Iran, one senior U.S. official pushed back expectations that a formal, preliminary deal would be reached this month.

Instead, the official told The Associated Press that negotiations are likely to reach a looser construct, more akin to an "understanding that's going to have to be filled out with lots of details" before their preliminary deal deadline in March and a self-imposed final deadline in June.

Until Wednesday, that first stage preliminary agreement had been described as a "framework agreement," noted AP.

Following a meeting with Iranian Foreign Minister Mohammed Javad Zarif, U.S. Secretary of State John Kerry issued what seemed to be a veiled jab at Israeli Prime Minister Benjamin Netanyahu, telling reporters that Washington is indeed aware of the potential nuclear danger Iran poses to other Middle Eastern countries.

Kerry said that the U.S. will only endorse an agreement that verifiably prevents Tehran from developing nuclear weapons.

"We continue to be focused on reaching a good deal, the right deal, that closes off any paths that Iran could have towards fissile material for a weapon and that protects the world from the enormous threat that we all know a nuclear-armed Iran would pose," Kerry said, reported the AP.

On Tuesday, Netanyahu delivered a much anticipated and highly controversial speech to the U.S. Congress in Washington, warning that the Obama administration was negotiating a bad deal with Iran that would "pave Iran's path to a bomb" and threaten the entire world.

But Kerry said Wednesday, referring to the prime minister, that politics and external factors would not distract from the goal of reaching a deal with Iran.

"No one has presented a more viable, lasting alternative for how you actually prevent Iran from getting a nuclear weapon," Kerry said, reported Reuters.

"So folks, simply demanding that Iran capitulate is not a plan. And nor would any of our P5+1 partners support us in that position."

The other partners helping the United States in the negotiating process, referred to as P5+1 countries, are Russia, China, France, Britain and Germany.