I don't doubt that Mitt Romney is devoted to Israel, and I don't doubt that he's committed, in his own mind, to stopping Iran from gaining nuclear weapons. But the question here has to do with the type of devotion he expresses, and with his ability to actually stop Iran. I've argued before that Romney would face some obvious problems in the crisis with Iran: His foreign policy team will be inexperienced; as a Republican, he would face extraordinary opposition from a revitalized anti-war movement and from Democrats in Congress; he himself doesn't want to gain the reputation George W, Bush gained for himself, and so on. Obama, as I have argued in this space, over and over again, is in a better position to carry through his promise to keep Iran from going nuclear, and he has proven he is cold-blooded enough to use force if he thinks American interests are at stake. As he has said, over and over again (including in this space), he believes it is a "profound" American national security interest to stop Iran. In the matter of Iran, I believe Israel is better off with Obama in the presidency.
There is one wrinkle: I've also argued that the Iranians may be more apt to believe that Romney is crazy enough to attack them, and so they might be more apt to negotiate an end to their nuclear program for fear of a Republican president (there's not much evidence available to suggest that the regime is frightened of Obama, in part because Obama has been undermined on occasion by members of his own administration who have publicly labeled the military option a terrible idea. It may be a terrible idea, but it doesn't help Obama's negotiating position when his own employees say so publicly). One reason to discount a potential Romney-is-crazy-like-Nixon ploy is that I have serious doubts about whether the Iranian regime will give up its nuclear program, no matter who is president.
One final-for-now thought, that runs counter to a certain prevailing narrative about what it means to be pro-Israel. I'll pose it as a question: Is an American president "pro-Israel" if he neglects to mention to the Israeli leadership his worries about Israel's future as a Jewish-majority democracy, in which freedom of speech is sacred and the rights of minorities are protected? Is it "pro-Israel" to not point out the various demographic, moral and security challenges presented to Israel by the continued expansion of settlements on the West Bank? Obama did a poor job, in his first term, helping Israelis analyze their existential dilemmas, save the existential dilemma posed by an Iranian bomb. But if wins, he could try to re-set (to borrow a term) his relationship with Netanyahu, and he could raise the sort of questions privately that need to be asked. (I'll address the issue of whether putting public daylight between Israel and America is a good, or bad, thing, from an instrumental, not moral, point of view, in a later post).
If I thought that Romney were willing to ask these hard questions about Israel's future, I would be more apt to suggest that he would be good for Israel. But there's no proof that he would engage Netanyahu in this sort of dialogue. Being pro-Israel means many contradictory things these days: Standing against Iran's annihilationist impulses; defending the justice of the Jewish national liberation movement; thwarting the jihadist desire to hurt Jews. But it also means finding a way to help Israel think through the consequences of its policies on the West Bank, before it is too late. The truth is, Israel isn't best served by either Romney or Obama. What it needs is a concentrated dose of Bill Clinton.