At a war veterans' convention in Nevada this week, Romney accused Obama of being "fond of lecturing Israel's leaders."
"He has undermined their position, which was tough enough as it was," Romney said. The "people of Israel deserve better than what they have received from the leader of the free world."
Obama rejects the criticism and points to unprecedented security cooperation with the Jewish state.
Three years after he came into office with Israeli-Palestinian peace at the top of his foreign policy priorities, Obama recently acknowledged that his efforts there have failed. Peace talks have been deadlocked more than three years.
Obama, who tried to persuade the Arab world that he was an honest broker, lost the Palestinians' trust by refusing to follow up tough talk with action when Israel defied his call to halt settlement construction on occupied land Palestinians seek for a future state.
The Palestinian leadership in the West Bank has refused to resume negotiations without a settlement construction freeze and went ahead with a statehood campaign at the United Nations, over the president's objections.
Palestinians fear Romney would be softer on Israel than Obama. Palestinian politician Hanan Ashrawi said that would doom any chance for resolving the Israeli-Palestinian conflict and establishing a Palestinian state on lands Israel captured in the 1967 war.
"American foreign policy in the region is shaped by Israel and determined by what's good for Israel, and not even what's good for the U.S.," Ashrawi complained.
Romney "will probably try to take it a notch higher," she said, and if the U.S. refuses to put any pressure on Israel, "then there's no chance for peace."
Obama's tense relations with Netanyahu have created the perception that U.S.-Israeli relations have deteriorated. During one of Netanyahu's White House visits, Obama extended none of the trappings, like a joint news conference, usually accorded to an important ally.
Associated Press writer Kasie Hunt in London contributed to this report.
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