Snellville, Ga. -- Mitt Romney took President Obama to task Sunday, calling his foreign policy a failure and warning that if he's reelected "Iran will have a nuclear weapon."

"This president has failed," Romney told a crowd of more than 1,200 at a pancake brunch. "It's pretty straightforward in my view -- if Barack Obama gets re-elected Iran will have a nuclear weapon and the world will change if that's the case. ...

"This president failed to speak out when the dissidents took the streets in Tehran," Romney continued. "This is a president who has failed to put in place crippling sanctions against Iran. He's also failed to communicate that military options are on the table and in fact in our hand."

Romney's criticisms came after Obama took a swipe at the Republican presidential hopefuls, declaring in a speech to the American Israel Public Affairs Committee -- or AIPAC -- there's been too much "loose talk" of war with Iran.

Republicans, including all four candidates running for president, remain skeptical of the Obama administration's foreign policy, saying it has allowed Iran to take steps toward nuclear proliferation.

They also accuse the president of not supporting America's strongest ally in the region -- Israel -- unconditionally. But the president pushed back on that Sunday, declaring emphatically, "When the chips are down, I have Israel's back."

Iran maintains its nuclear program is for peaceful purposes only -- intended to provide the Islamic republic with nuclear power.  But the international community believes differently and fears that a nuclear Iran could spur an arms race in the Middle East or worse -- that it could allow fissile material get into the hands of terrorist organizations, something Romney warned against.

"If they have fissile material, then the world has changed. And I'm not willing to allow your generation to have to worry about a threat from Iran or anyone else that nuclear material be used against Americans."

Romney will address AIPAC Tuesday morning via satellite.