The Obama administration took two steps back from its push for a prompt attack on Syria, allowing several weeks more for diplomacy on eliminating Syrian chemical weapons and acknowledging that an eventual United Nations resolution wouldn’t threaten force, senior administration officials said.

The reversals on Friday—after a week that began with President Barack Obama insisting that Congress urgently approve military action—came as U.S. officials said talks with Russia were producing a road map for shutting down Syria’s weapons program.

Mr. Obama and his team have turned to the Russian diplomatic proposal as a way to degrade Syrian President Bashar al-Assad’s ability to carry out chemical attacks without resorting to military strikes, which had drawn opposition at home and abroad.

Secretary of State John Kerry and his Russian counterpart Sergei Lavrov extended talks to continue for a third day in Geneva on Saturday, to settle on a more formal framework for disarming Syria and on benchmarks to gauge success.