BEIRUT—The Syrian regime, emboldened by battlefield victories, is pushing a political solution to end the war that keeps President Bashar al-Assad in power, in defiance of the agenda supported by Russia, his vital ally.

The plan will begin to unfold with Syrian parliamentary elections on Wednesday; the following day, Mr. Assad’s representatives will travel to peace talks in Geneva, where they are expected to push for a resolution to the conflict on Mr. Assad’s terms.

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