JQuery+AJAX partial in form_for

Hi! I want to render partial which depends on form builder "f". How can
I do it using AJAX+JQuery

Files
#new.html.haml
%h1
  New order
- form_for(@order) do |f|
  = f.error_messages
  %div#partial
    = render "#{@order.current_step}_step", :f => f

#create.js.erb
$("#partial").empty();
$("#partial").append
    ( <%= render "#{@order.current_step}_step", :locals => {:f=>f}%>);

The error
  undefined local variable or method `f' for ActionView::Base