As a Member of the Croatian Parliament, he fought for generational political changes, against foreclosures, evictions and debt bondage, and against the imposition of genetically modified food. He campaigned for monetary sovereignty, agricultural development, the protection of small producers against large corporations, and for the rights of whistle-blowers, producers and borrowers with Swiss franc-denominated loans, as well as for the protection of the environment and animals.
During his mandate, he met with many citizens and always endeavoured to either solve their problems or do as much as he could to help. Moved by citizens’ problems, he wrote hundreds of parliamentary questions to the government, ministers and national institutions, and submitted hundreds of letters, statements and criminal complaints against corrupt politicians, judges and other officials and against a number of companies and institutions.
A true activist, Sinčić travelled all over Croatia in order to understand the conditions in which his fellow citizens are living and fully grasp their wants and needs.
He tabled dozens of bills, including legislation on: electronic voting, investigating the origins of property, enforcement, protecting whistle-blowers, preventing conflicts of interest, the Zagreb earthquake relief fund, the Chamber of Commerce, and protecting against non-ionising radiation, as well as acts supporting the legalisation of cannabis, among others.
Through his work in the public eye and in the Croatian Parliament, he has sparked public debates on a number of societal topics, such as foreclosures, evictions, the credit system and outstanding debts, and corruption. These issues were previously marginal concerns or were not even on the public radar. He has therefore raised awareness among Croatians, as well as their aspirations for generational political change.
In the 2019 European elections, Sinčić won the largest number of votes and so became a Member of the European Parliament.
In the European Parliament, he became a member of the Committee on the Environment, Public Health and Food Safety and the Delegation for relations with India. He is also a substitute member of the Committee on Agriculture and Rural Development, Committee on Industry, Research and Energy and the Delegation to the EU-Russia Parliamentary Cooperation Committee.
As an MEP, he has continued to champion national policy topics, as well as taking up certain new European-wide issues which he included in his election campaign, such as the common fight against corruption, and calls for organic farming, the protection of the environment and oceans, and building world peace.