Radic had in July 1923 gone abroad to seek support for a Croatian peasant republic but returned disappointed to Zagreb in August 1924 and was imprisoned until July 1925.

Accepting the 1921 centralist constitution, however, he entered the government in 1925 but returns to opposition in 1927.

In an unexpected collaboration with Svetozar Pribicevic, a Serbian Democratic leader, he forms the peasant-democratic alliance that demands a federalist reorganization of the Kingdom of the Serbs, Croats, and Slovenes.