Nuclear expert and former U.S. Sen. Sam Nunn, D-Ga., is publicly backing the Iran nuclear deal negotiated by the United States and other world powers.

Nunn spent much of his Senate career on nuclear non-proliferation and now runs the Nuclear Threat Initiative. Here's a piece of what he told Denis O'Hayer and Jim Burress WABE-90.1 FM, with full audio here:

"The other dimension is the Iranian behavior. There's no question that the Iranian behavior in the region is destabilizing, whether it's viz a viz Syria, whether it's Hezbollah -- an organization we've branded as terrorist -- whether it's Hamas, whether it's in Yemen.

"But this negotiation was not aimed at this behavior. And these debates are getting very much mixed between those goals, because if we had aimed it for instance Syria behavior of Iran, or Hezbollah or Hamas, we wouldn't have had Russia participate. And we probably would not have had much enthusiasm for the oil embargo that our European allies have put on.

"So we have to parse this a little bit and say what was the agreement aimed toward? What were the negotiations aimed toward? What were the U.N. resolutions aimed toward? And what was the economic embargo -- which has been very effective -- aimed toward? And it was to prevent them from getting a bomb. And this agreement does make it much more difficult -- you wouldn't say impossible -- but it makes it extremely difficult for them to achieve that goal of getting a bomb over the next 10 or 15 years. ...

"When you get right down to it, what we're doing: We're buying time. We're not getting an insurance policy that they'll never have a weapon."

Nunn added that the George W. Bush administration also aimed any negotiations at halting a bomb, not Iran's behavior in the region. He also countered the argument that lifting sanctions will help Iran's economy, giving it more funding to build a bomb:

"And the assumption of that argument is that we can continue the embargo. And the United States can make that decision and our allies --including Russia and China -- will all salute and say, 'Yes sir, Uncle Sam, we'll go along with that.' And our European allies will continue to not buy oil, which has been devastating to the Iranian economy. That assumption is false."

While Republicans are certain to line up against the deal, President Barack Obama only needs Democrats to hold up his veto. A vote is expected in September, after a fierce two months of lobbying.

Obama has been wooing Democrats on the golf course and on Air Force One for his trip to Africa. Nunn's comments could provide an additional talking point.