Tomás is an associate for Democracy Without Borders in Spain. From 2017 to 2019 he was Regional Coordinator for Latin America for the Campaign for the Creation of a United Nations Parliamentary Assembly. He collaborates with federalist organizations such as the Young European Federalists (JEF) and the Union of European Federalists (UEF) in Spain as well as Democracia Global in Argentina and other members of the World Federalist Movement (WFM).