ASP.NET MVC - Pass Json String to View using ViewData

I'm trying to pass Json to my View using ViewData

Controller

ViewData("JsonRegionList") = Json(RegionService.GetActiveRegions())

view

        $("input#UserRegion").autocomplete({
                source:"<%: ViewData("JsonRegionList").ToString %>",
                minLength: 3,

but the problem I'm running into is the output source looks like

        $("input#UserRegion").autocomplete({
                source:"System.Web.Mvc.JsonResult",
                minLength: 3,

which is obviously not right. Am I missing something basic?