"This is about the economic and monetary union but for the EU as a whole," he said.
"The commission will, therefore, set out its views and explicit ideas for treaty change in order for them to be debated before the European elections."
"We want to put all the elements on the table, in a clear and consistent way, even if some of them may sound like political science fiction today. They will be reality in a few years' time."
Mr Barroso's announcement that he will set out plans for a European federation next spring, before elections to the European Parliament in May 2014, will further deepen Conservative divisions over the EU.