AfD members are under surveillance of the German secret services. Now the services will have to carry out surveillance also of the 13 percent of the German population that voted for AfD.
No evidence given. The German intelligence services have been tasked with the collection and the analysis of information on efforts directed against the free democratic basic order or against the existence and the security of the Federation or one of its States or aimed at unlawfully hampering constitutional bodies of the Federation or one of its States or their members in the performance of their duties or jeopardising foreign interests of the Federal Republic of Germany by the use of violence or the preparation thereof or directed against the idea of international understanding (article 9, para. 2 of the Basic Law (Grundgesetz, GG)), especially against the peaceful coexistence of peoples and intelligence activities carried out on behalf of a foreign power (counter-intelligence).
Moreover, in conformity with section 3 (2) of the BVerfSchG, BfV contributes to counter-sabotage and personnel/physical security. Exercising your democratic right to vote for what you wish is neither of the above. https://www.verfassungsschutz.de/en/about-the-bfv/tasks/what-exactly-are-the-tasks-of-the-domestic-intelligence-services