His doctoral thesis Socio-political Views of P. Świtkowski, written under the supervision of I. Chrzanowski, he defended it in 1927, while he received his Master of Laws degree from the University of Warsaw in 1929.

In 1930-35 he was a Sejm deputy from the Skierniewice-Rawa district, and from December 1938 until the outbreak of war he was leader of the National Club in the Warsaw City Council.

Together with Piłsudskiites (Ignacy Matuszewski, August Zaleski) and monarchist Stanisław Mackiewicz (Cat), the National Party led by Bielecki was the core of the opposition against the provisions of the Sikorski-Mayski agreement of July 1941 on “amnesty” for Polish citizens and undermining the eastern border of the Republic, and from November 1944 - one of the pillars of the “anti-Yalta” government of Tomasz Arciszewski.

At the same time, in December 1942, he put forward as the first Polish politician officially, on behalf of the SN, the demand to move the western border of the Republic on the Oder and Lusatian Neisse.

Widely appreciated as an activist and organizer, Bielecki is less well known as an ideologue of the “young” National Democracy, i.e., the generation that had already begun its activities in independent Poland.

Like that entire generation of nationalists, Bielecki embodied a firm turn to Christian nationalism, ridding himself of the remnants of liberalism and positivist agnosticism.

He distinguished between two types of nationalism: 1/ “savage, pagan, revolutionary, integral, leftist, imperialist, materialist, biological, negative, anti-parliamentary and closed”, and 2/ “enlightened, Christian, evolutionary, republican, ‘bourgeois’, defensive, spiritualist, humanist, constructive, democratic, open”, identifying with the latter series of values and arguing that it marked Dmowski's national idea.