On May 22-25, 2014, voters in the countries that are part of the European Commission elect a new European Commission Parliament. Afterwards, the European Parliament will elect a President of the European Commission. Ordinary voters in Europe do not vote directly for president of the European Commission.
Nevertheless, five European parties are choosing a proposed president, in advance of the voting for Parliament, so that voters will have a sense of which presidential candidate these particular parties prefer. The five parties that are doing this are: European People’s Convention (which is a coalition of Europe’s center-right parties), the Party of European Socialists, the Alliance of Liberals and Democrats for Europe Party, the Party of the European Left, and the Green Party. Here is a wikipedia article about the 2014 European election.
Among these five parties, only the Green Party is holding a European-wide “presidential primary.” The vote is being conducted on the internet and any citizen of a nation within the European Union who is at least age 16 may participate. There are four Greens running, and the primary will choose two of them, to guarantee that at least one woman is in the running. They four Greens running are Jose Bove of France, Monica Frassoni of Italy, Rebecca Harms of Germany, and Ska Keller of Germany. For more about the Green presidential primary, see greenprimary.europeangreens.eu.