RedirectResult and cookies

Question

I have a method that figures out what to do with a user after

    protected override ActionResult RedirectFromReg1(IPrincipal u)
            {
              if something....
                 {
                     return RedirectToAction("LogIn", "Account");
                 }
            return null;
     }

The calling code then returns the ActionResult or continues processing depending on if it is null.

The trouble is, that when you return a RedirectToAction, one loses all cookies set before the RedirectToAction. If I redirect to a string, I use response redirect and not end the request, keeping the cookies.

Response.Redirect(redirectTo, false);

Is there a similar way to use ActionResult or must I pass around strings? The potential universe of redirectTos is so large I'd rather not cache the cookie in the ViewData and re-add it in the request if I can avoid it.