In theory, the European Union's parliamentary elections are the most international in the world. The winners serve in a multinational legislature. They speak to one another with the help of hundreds of translators. They are members of transnational parties: In the Parliament buildings in Brussels and Strasbourg, center-left MEPs from across Europe sit with the Party of European Socialists, center-right MEPs caucus with the European People's Party, and so on.
Nevertheless, European elections have never quite fulfilled this multinational promise. Usually they consist of dozens of campaigns, each dominated by national debates. In most years, the German Christian Democrats don't go on the hustings on behalf of their Swedish counterparts, and the Portuguese input into the Slovakian elections is pretty negligible.