ANKARA, Turkey — Prominent Syrian opposition figures are presenting a plan for a political transition should President Bashar Assad's government fall.

The report by about 300 activists, including military leaders and members of the main opposition group, calls for disarmament of militias and remaking security services. Under the plan, a new national assembly would draft a constitution based on an earlier one written in 1950. The final document would then go to a referendum.

The activists envision a government with both a president and a parliament to offer checks and balances, and recommend creating an independent judiciary.

The roadmap to be released Wednesday in Istanbul comes as the Assad government has consolidated control over central Syria and around the capital, Damascus.