WASHINGTON (Reuters) - President Barack Obama on Sunday refused to back away from his new Middle East peacemaking proposals that have angered Israel, as he addressed the Jewish state's staunchest American supporters amid a deep rift in U.S.-Israeli ties.

But Obama, speaking to the pro-Israel lobbying group AIPAC, sought to reassure Israel's backers of his commitment to the Israel three days after he endorsed a longstanding Palestinian demand on the borders of their future state, drawing a rebuke from Israeli leader Benjamin Netanyahu.

(Reporting by Matt Spetalnick and Caren Bohan; Editing by Jackie Frank)