Secretary of State John Kerry said that the negotiations between Iran and the five permanent members of the U.N. Security Council, plus Germany, in Vienna are "making progress" as the new Tuesday deadline looms.

Kerry and Iranian Foreign Minister Mohammad Javad Zarif, who met privately earlier Friday are meeting with the entire group after a 24-hour period without a meeting "because we had our teams working very, very hard and very diligently all day in order to maximize progress," Kerry said. "And I think it's fair to say that both sides are working extremely hard with great sense of purpose in a good-faith effort to make progress, and we are making progress.

"So we have a lot of work to do," Kerry continued. "We've got some tough issues, but there's a genuine effort by everybody to be serious about this and to understand the time constraints that we're working under. So we will continue to work — tonight, tomorrow, Sunday — and we certainly both want to try to see if we can arrive at a conclusion."

The deadline was extended a week to see if a final agreement palatable to all sides and that conforms to the interim deal struck in Lausanne, Switzerland, on April 2 could be met.

"Oh, we're just working," Zarif added before the duo entered the larger meeting. "I agree, we're all trying very hard in order to be able to move forward, and we have made some progress. There are still tough issues to discuss and to resolve, but I think with political will, we will."

Foreign policy experts and skeptics in Congress are lobbying Obama to walk away from the negotiations if the Iranians refuse to allow inspectors to verify it is not creating a nuclear weapon and limits its enrichment to peaceful purposes for at least 10 years.