Sen. Bob Menendez Says Iran’s Optimism on Nuclear Deal Makes Him ‘Anxious’

— -- With signs of progress toward a nuclear agreement with Iran, Sen. Robert Menendez said today that comments by one of Iran's vice presidents about the deal make him "anxious."

Iranian Vice President Masoumeh Ebtekar told ABC News' Martha Raddatz she is optimistic about the terms of a potential deal, saying "it will signify an opportunity for both sides to work together to resolve some of the issues" facing Iran.

"It makes me anxious because what a deal looks like is incredibly important," Menendez told ABC's George Stephanopoulos on "This Week. "And the problem here is that we have gone from preventing Iran having a nuclear ability, to managing it. And what we are doing is basically rolling back sanctions for verification."

Menendez, who is a senior Democrat on the Senate Foreign Relations Committee, stressed the importance of preventing Iran from developing nuclear arms.

"We cannot accept Iran having a nuclear weapon. Period," Menendez said. "That's the premise we started on. That's the premise we should finish on."

On Friday, the negotiations stretched past their already extended deadline. After meeting with Iranian Foreign Minister Javad Zarif on Sunday, Secretary of State John Kerry expressed optimism that a deal will soon be reached.

"I think we're getting to some real decisions so I will say -- because we have a few tough things to do -- I remain hopeful," Kerry told reporters in Vienna, where the negotiations are taking place.

Menendez has been critical of the Obama administration's handling of the talks and recently introduced a bill that would extend the Iran Sanctions Act of 1996 for another 10 years.

If a deal is reached, Congress will have 60 days to review it, but Menendez did not outline what terms he would consider acceptable.

"I'm going to judge it when I have all of the elements of it," he said. "I'll judge the agreement based upon what it is."