GENEVA — An Iran nuclear deal within reach, U.S. Secretary of State John Kerry and five other foreign ministers focused Saturday on the fine print of a draft agreement meant to satisfy not only the other side, but also to placate powerful domestic forces that fear giving too much for too little in return.

Diplomats refused to spell out details of the talks, held in a five-star Geneva hotel. But comments from both sides suggested negotiations focused on detailed wording that could be key in shaping an agreement that both sides could live with.