Russia and China could certainly push syria to stop the violence and push for enough reforms to force assad to appease his people while retaining power. Iran is also not interested in a power change, but again they wield influence in syria to help stop the slaughter, but as we have heard from them already they not only condone it, they applaud it. Turkey could force the issue if they were determined to see it through. They have the military to effect change, they also share a border with syria so getting into syria for them wouldn't be too hard. They and the arab league could force a change of power, but I think they lack the will to do what it would take to make the change happen. Besides they are prob. just waiting for the US to do the work for them, which I hope we don't do.