The Republican candidates, except for Ron Paul, are all hot and bothered about stopping Iran from getting the atomic bomb. But they never mention Israel's bomb. And they pretty much ignore Pakistan's bomb, and India's bomb. And they never mention America's bombs, Russia's bombs, China's bombs, Britain's bombs, etc. The responsible way to stop Iran would be to have a genuine, functioning non-proliferation regime, not one full of loopholes for any country determined to stay outside the regime.
The main impetus behind Iran's drive to build a bomb is Israel's bomb. It's not clear that the Iranians actually have a dedicated bomb development program, but it is clear that they want a nuclear infrastructure that would allow them to build a bomb in a relatively short time, if they decided that they needed one. And why would they need one, probably because they felt threatened by Israel. Of course, Israel feels threatened by Iran. But the cold war was basically about mutual threats between the US and Russia, and we both survived, so far.
If we were serious, about getting Iran to back off of its nuclear program, we all have to get serious about nuclear arms. The US and Russia both have to seriously disarm. Israel, Pakistan, and the rest have to give up their nuclear programs. George Bush actually increased cooperation with India's civil nuclear program, despite is military nuclear program, a step undermining non-proliferation globally, although it may have made sense bilaterally.
If the US were to invade Iran to shut down its nuclear program, by rights it should also invade Israel, Pakistan, North Korea, India, and other problem countries. Arguably, the older nuclear powers, the US and Russia, are grandfathered under the regime, although they are theoretically obligated to disarm, too.