International powers negotiating a nuclear deal with Iran failed to meet another deadline on Tuesday, the second missed target in a week, raising the prospect of an open-ended diplomatic process over an issue on which President Barack Obama has staked his foreign-policy record. Senior administration officials in Vienna and Washington said progress was still being made and negotiators “have never been closer” to a comprehensive deal to curb Iran’s nuclear program in exchange for lifting international sanctions. Mr. Obama has said talks would end in a deal that reflects a framework reached in April, or with no agreement at all. But with negotiations making little headway, the White House on Tuesday laid the groundwork for a third outcome: continuing talks while keeping in place a November 2013 interim agreement that provided Iran with limited sanctions relief in exchange for rolling back parts of its nuclear program. Such an outcome […]