BEIRUT, Lebanon — A growing number of Syrians on both sides of their country’s conflict, along with regional analysts and would-be mediators, are demanding new strategies to end the civil war, based on what they see as an inescapable new reality: President Bashar al-Assad is staying in office, at least for now.

They say the insistence from the United States-backed opposition that Mr. Assad must go before peace talks can begin is outdated, failing to reflect the situation on the ground. Rather, they say, a deal to end or ease the violence must involve Mr. Assad and requires more energetic outreach to members of his government and security forces, with concrete proposals and reassurances that could bring compromise.

They also contend that the American-backed exile opposition coalition that remains at the center of Washington’s policy has little relevance and no respect from combatants on either side. These critics of American policy say that the United States and its coalition ally are helping guarantee that diplomacy remains paralyzed as Syrians die.

On Friday, the exile coalition declared it would not attend a meeting in Moscow that would have brought it together with Syrian government officials for the first time, albeit to focus narrowly on addressing Syria’s deepening humanitarian crisis. The sticking point: Moscow also invited Assad opponents who are more willing to compromise.