The United Kingdom is set to have a referendum by the end of 2017 not to remain in the European Union. This so-called In/Out referendum (which could the U.S. be held early us June 2016) may well result in Britain's exit from the EU, colloquially known as ‘Brexit’. However, Brexit gives political and economic impact to European Union. European Union as regional forum receive political impact that will loose the capacity in global political arena because Britain would open opportunities to form stronger coalition grooves, and opened the container to build a new political coalition. Brexit resurges the ideas of Neo mercantilism as the principle political economy in European Union after the subsidiarity ideas.