In addition to regional movements, supranational organizations that promote progressive integration between its members gained force in the end of the 20th century. Most of these organization are inspired on the European Union and, although most of the states are reluctant with it, the concept of unionism is often present. Lord Durham in his '1839 Report; clearly the difference between a full legislative union and a federation: Two kinds of union have been proposed – federal and legislative.

By the first, the separate legislature of each province would be preserved in its present form and retain almost all its present attributes of internal legislation, the federal legislature exercising no power save in those matters which may have been expressly ceded to it by the constituent provinces. A legislative union would imply a complete incorporation of the provinces included in it under one legislature, exercising universal and sole legislative authority over all of them in exactly the same manner as the Parliament legislates alone for the whole of the British Isles. The real union is a union of two or more states, which share some state institutions; however they are not as unified as states in a political union and almost exclusively brought about a downfall of sovereignty of the politically weaker constituent. Sometimes, however, a real union came after a period of a political one.

(wikipedia, 22-12-12)

In particular, a very ambitious economic federation combined with a rules-based approach to policymaking and indirect legitimacy, as proposed by some in Germany, will likely be unsustainable. Equally, it would be risky to introduce more political competition in a limited economic federation working on very narrow rules, which might lead to political and social unrest and instability at the national level. Nor can the German model of constitutional democracy simply be exported to the whole of the EU. The wrong approach to political union could lead to a failure to stabilise and
legitimise monetary union or a split at the core of the eurozone. Thus an attempt to overcome the crisis could push the EU off a political cliff.

For much of the history of European integration, the final goal of political union – the famous finalité politique – was seen as a distant one. Even when attempts were made to define it – for example, in the European Convention and the Constitutional Treaty – they failed completely. But the euro crisis has led to a massive transfer of power to the EU level and made political union a real possibility. Political initiatives by European Council President Herman Van Rompuy and German Foreign Minister Guido Westerwelle, together with the rulings of the German Constitutional Court and European Commission President José Manuel Barroso’s recent call for a “federation of nation states” have kicked off a new debate about political union. But while many pro-Europeans now agree that political union is necessary to save the euro, they often have in mind very different things.

In particular, European leaders must make three choices about what type of political union they want. The first choice is between a limited economic federation aimed at stabilising the euro and a full economic federation taking on traditional nation-state tasks such as taxation, social welfare, and redistribution. The second choice is between a rules-based federation with a very small margin for policy innovation and flexibility and one with ample discretionary powers and policy instruments. The third choice is between a political system that relies on indirect legitimacy and is governed mostly through intergovernmental mechanisms and one that draws on direct legitimacy instruments and confers ample executive authority to supranational institutions such as the European Commission.

Actual, but more than a decade ago, the content of the Wallenberg speech on Reuniting Europe: Our Historic Mission from Jacques Delor held 14 November 1999 at the Aspen Institute. Still touches the section 'The political project' out of this speech the heart of the matter:

It is not possible to discuss this subject without being clear and frank. In a European Union of thirty Member States, we cannot retain the same objectives and aspirations set out by the Maastricht Treaty since, once the number of partners around the table have increased, the differences in perception between Member States make it very difficult to reach agreement on common actions, in point of both the means and the bjectives. Look at the difficulties already experienced by the European Union of fifteen in implementing all the provisions of the Maastricht Treaty.

This is obvious in connection with the two areas in which new developments in the building of a united Europe are expected - foreign policy and defence, or justice and police affairs. The discussions under way in these two areas make this abundantly clear. The delay in developing these policies is not attributable to the unsuitability of the institutions, as is sometimes claimed, but to political - and sometimes philosophical - visions which translate differently even within the Europe of fifteen Member States, that is, the idea which each of us has of the world role of our own country, and also to diverging conceptions of the exercise of sovereignty.

In day-to-day relations between Member States, the most important thing is to give political responses to certain basic questions. For example: who wants to take on the means to implement what are known as the Petersberg missions, participation in peace-keeping operations, repatriation of refugees, humanitarian aid and, if need be, intervention in a crisis so as to restore a peace?

Or how to quantify the European military effort in relation to the Atlantic Alliance and do we agree to share the burden if we really want a European pillar for the Atlantic Alliance? Does this entail - and it should always be borne in mind – the possibility of the European Union specifically carrying out Petersberg missions? Or again, in the field of justice, are we in basic agreement on the policies to implement jointly so as, for example, to set up transnational teams of police officers or to terminate certain money-laundering practices?

Rather than a predetermined definition of the institutional framework, it seems to me to be important for those concerned to agree on a "Community method", that is to say, to make use of what I call the "institutional triangle" - the Council, the Commission and the European Parliament - under the direction, as it should be, of the European Council, that is to say, the Summit of Heads of State and of Government, and subject to the supervision of the Court of Justice. Experience has shown that when it diverges from that method, Europe gets nowhere.

It remains to be seen whether the method will remain effective when there are twenty-five or thirty around the table. I have good reason to doubt it: at fifteen, taking the views around the table in the Council of Ministers takes forever and the participants tend to get up and leave once they have spoken in order to speak to the press without waiting for the end of the debate. You can imagine what that will be like with thirty! ... In truth, the whole operation of the Council of Ministers needs to be rethought if we want citizens to be able to follow the decision-making process, which is lost on them in the labyrinth of a procedure which may take months, if not years, with drafts circulating from committee to committee before they are examined by the appropriate bodies of the Parliament and come back at last to the Council.

I do not believe either in the virtues of the so-called ratchet theory according to which political progress emerges as if by magic from economic integration. I have therefore never believed that the Economic and Monetary Union - for which I worked so hard - would, as some claimed, serve as a springboard for political union.

No, we have reached the stage of development of European affairs where we cannot avoid a direct political approach to the issues. This is why I keep asking the same question: "What is it we want to do together? How far are we prepared to go to achieve together the things which matter to us and which we cannot, or can no longer do individually?"

I asked that question in my capacity of President of the Commission before the last enlargement, because I considered, not without reason, that it had to be answered before the three applicant countries at that time, Austria, Sweden and Finland, acceded. Those three countries’ objectives did not always coincide with those stated by the Twelve, particularly in view of their neutral status. I fear that I was preaching to deaf ears. It was as if the question was taboo, because by asking it one risked offending one party or another or harming a sort of blissful optimism which had to be preserved.

For my part, I still think that it is better to ask the real questions rather than sweeping them under the carpet and that there are fewer risks in revealing any potential disagreements before welcoming new partners than after having recruited them. It should therefore not come as a surprise that I have persisted, in public and in private, in asking men and women from the countries of central and eastern Europe, both political leaders and representatives of civil society and intellectuals, what objectives they hope to achieve by joining the Community.

Far be it from me - as you will appreciate - to attempt to dissuade them, as I told you in my introductory remarks. I am convinced that it is our historic mission to reunite Europeans in a single political entity, but I should like us to agree on the content of the marriage contract before choosing its general form. That is to say, before we define the institutions which will enable us to work together, since in order for those institutions to allow us to bring a joint project to fruition, that project must have been defined with sufficient precision.

This is also true of the States already in the Union at least as much as it is for those knocking on the door. Do we want to be faithful to the European contract which I would sum up as follows:
competition which stimulates, cooperation which strengthens and solidarity which unites? Do we have the will to give the European Union the means this contract requires? If so, I say without hesitation that the European budget will have to exceed the limits imposed by Agenda 2000 to which the German Presidency got the Fifteen to agree last spring. What I would like to see is all the conclusions drawn from the principle affirmed in his time by Hans Genscher, according to which no Member State can be made to go further than it can or wishes to do so, but that a State not wanting to go further may not prevent the others from doing so.