Iran deal: The mother of all congressional fights?

Lobbying efforts around the Iran nuclear deal are kicking into high gear and will only intensify over the next 60 days. With tens of millions of dollars being spent to stop the administrations efforts, some are calling it the mother of all congressional fights, reports CBS News correspondent Julianna Goldman.

"It isn't a, 'better deal,' -- some sort of unicorn arrangement," Secretary of State John Kerry said on Capitol Hill Thursday, pushing back against critics of the agreement forged with Iran by the U.S. and five other world powers. "The alternative to the deal that we have reached is not what I've seen some adds on TV suggesting, disingenuously."

But the administration is up against the country's biggest pro-Israel lobbying groups, including The American Israel Public Affairs Committee (AIPAC) and the Republican Jewish Coalition, which are spending up to $40 million to try and kill the deal -- a lopsided figure compared to the $10 million spent by groups backing the administration, such as liberal pro-Israel group, J-Street.

"I would describe it as one of the largest congressional fights we will see in our lifetime," Republican Jewish Coalition spokesman Mark McNulty said.

President Obama has threatened to veto any bill that rejects the Iran accord, but he needs support from his own party to prevent a possible override.

On Thursday, Mr. Obama met about a dozen undecided house Democrats, including Rep. Adam Schiff.

"I'm going to try to tune out the external, you know, over the airways campaigning, (and) really dig into the merits and decide on the merits," Schiff said.

Separately, a group supporting Sen. Marco Rubio's presidential bid has spent more than $4 million on ads to fight the nuclear accord.

To put the estimated $40 million budget devoted to that cause in perspective, one watchdog group told CBS News that gun advocacy groups spent just half that to defeat gun control legislation after the Sandy Hook shooting.