Disabling connection to ELPA repository

Question

Is it possible at startup to disable the connection to the ELPA repositories?

I have

(when (>= emacs-major-version 24)
  (require 'package)
  (package-initialize)
  (add-to-list 'package-archives '("marmalade" . "http://marmalade-repo.org/packages/") t))

in my init.el and every time I start emacs, it does connect to the repositories. I would prefer to do that manually time to time.

Answer 1

Using the package-spec.el package makes the connection happen.