In the 20th century, American politicians with ethnically diverse constituencies were advised to visit the “three I’s” — Ireland, Italy and Israel. Mitt Romney is heading to the third of those this summer on a mission he hopes will burnish his image with American supporters of the Jewish state. Fair enough, but in establishing his bona fides as a friend of Israel, the GOP candidate for president must be careful what he promises.

Romney has tried to capitalize on a perception that President Obama is insufficiently attentive to Israel’s interests. The supposed evidence was Obama’s endorsement of a solution to the Israeli-Palestinian conflict based on Israel’s 1967 borders with Jordan “with mutually agreed swaps, so that secure and recognized borders are established for both states.” Never mind that in espousing a two-state solution, Obama was echoing his GOP predecessor, George W. Bush.

Romney has also accused the president of being an unreliable ally of Israel and of “fretting” while Iran moves to acquire nuclear weapons.)

Romney said at a primary debate that in his administration, “we will not have an inch of difference between ourselves and our ally Israel.”

After Newt Gingrich made a remark critical of Palestinians, Romney said: “Before I made a statement of that nature, I’d get on the phone to my friend Bibi Netanyahu and say: ‘Would it help if I say this? What would you like me to do?’“

Martin S. Indyk, a U.S. ambassador to Israel in the Clinton administration, told the New York Times that Romney’s comment implied that he would “subcontract Middle East policy to Israel.”

Presidents have to remain independent enough to make their own foreign policy decisions. Romney should be mindful that in the future, a President Romney might find that Israeli and U.S. interests are more than an inch apart.