How to stop indentation with spaces for python files in vim

I have done all i can in .vimrc:

$ cat ~/.vimrc 
set nocompatible
syntax enable
filetype plugin on
" Allow recursive file find
set path+=**
set wildmenu
" stop using spaces for tabs!
filetype indent off
set noexpandtab
set tabstop=4
set shiftwidth=4

However, something is still loading the substitution of tabs with spaces. How do i turn it off?