LAUSANNE, Switzerland (AP) — Nuclear talks between Iran and six world powers could be extended past Tuesday's deadline for the outline of an agreement if enough progress is made to justify it, the White House said.

Tuesday's statement by White House press secretary Josh Earnest suggested that talks meant to produce an outline that would allow the sides to continue negotiations until the June 30 final deadline had not bridged all gaps — but that the sides were working to produce a text with few specifics, accompanied by documents outlining areas where further talks were needed.

"If it's necessary — and, when I say if it's necessary I mean if it's midnight and a deal has not been reached but the conversations continue to be productive — we'll be prepared to continue the talks into tomorrow," said Earnest.

He said President Barack Obama had been updated on the latest status of the talks. He also said it was possible that Obama would be in touch with members of the negotiating team.

"If we are making progress toward the finish line, than we should keep going," Earnest added.

Officials earlier said that they hoped to wrap up six days of marathon talks with a statement agreeing to continue negotiations in a new phase to control Iran's nuclear ambitions.

They had set a deadline of Tuesday for a framework agreement, and later softened that wording to a framework understanding, between Iran and the so-called P5+1 nations — the United States, Britain, France, Germany, Russia and China.

After intense negotiations, obstacles remained on uranium enrichment, where stockpiles of enriched uranium should be stored, limits on Iran's nuclear research and development and the timing and scope of sanctions relief among other issues. Senior Iranian negotiator Hamid Baeedinejad told reporters his side "can stay as long as necessary" to reach an agreement.

The aim has been a joint statement is to be accompanied by additional documents that outline more detailed understandings, allowing the sides to claim enough progress has been made to merit a new round, officials said. Iran has not yet signed off on the documents, one official said, meaning any understanding remains unclear.

The talks have already been extended twice as part of more than a decade of diplomatic attempts to curb Tehran's nuclear advance.

All officials spoke on condition of anonymity because they were not authorized to comment on the talks on the record.

If the parties agree only to a broad framework that leaves key details unresolved, President Barack Obama could face stiff opposition from members of Congress who want to move forward with new Iran sanctions legislation. Lawmakers had agreed to hold off on such a measure through March while the parties negotiated.

Obama has warned that passing new sanctions during the talks could upend the sensitive discussions.

Renewing his criticism of the unfolding deal, Israeli Prime Minister Benjamin Netanyahu said it would leave intact much of Iran's nuclear infrastructure, including underground research facilities, a plutonium reactor and advanced centrifuges capable of enriching uranium.

The U.S. says any final deal will stretch the time Iran would need to make a nuclear weapon from several months to a year. But Netanyahu said Washington initially promised "years" to a breakout time.

"In our estimate, it will be reduced to perhaps a year, most likely much less than that," he said.

The softening of the language from a framework "agreement" to a framework "understanding" appeared due in part to opposition to a two-stage agreement from Iran's supreme leader, Ayatollah Ali Khamenei. Earlier this year, he demanded only one deal that nails down specifics and does not permit the other side to "make things difficult" by giving it wiggle room on interpretations.

Russian Foreign Minister Sergey Lavrov, who left Lausanne Monday, arrived back in the Swiss city by late afternoon, an indication that an end to the talks could be near. That brought the full complement of all six P5+1 foreign ministers to Lausanne, where Kerry has been negotiating for a week with Iranian Foreign Minister Mohammad Javad Zarif.

In Moscow, Lavrov told reporters: "Prospects for this round of negotiations were not bad, and I would even say good."

Kerry and others said the sides have made some progress, with Iran considering demands for further cuts to its uranium enrichment program but pushing back on how long it must limit technology it could use to make atomic arms.

Officials in Lausanne said the sides were advancing on limits to aspects of Iran's program to enrich uranium, which can be used to make the core of a nuclear warhead.

Uranium enrichment has been the chief concern for more than a decade. But Western officials say the main obstacles to a deal are no longer enrichment-related.

Tehran says it wants to enrich only for energy, science, industry and medicine. But many countries fear Iran could use the technology to make weapons-grade uranium.

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White House Correspondents Julie Pace and Darlene Superville contributed to this story.