From 1993 he was President of the European Union of Christian Democrats (EUCD), until its merger with the EPP in 1996. Martens also negotiated with Finnish conservative politician Sauli Niinistö the merger of the European Democrat Union (EDU) into the EPP (formally concluded in 2002). The successful fusion of all centre-right European organisations into the EPP – currently the largest transnational European political party with 75 member-parties from 40 countries – is widely recognised as an important achievement of his European political legacy.