It was Poland:
For four decades before the historic Round Table Agreement, Poland had three legal political parties: the ruling communist PZPR and its two subservient coalition partners, the United Peasant Party and the Democratic Party. The first communist regime to gain power had outlawed the major pre-World War II parties—National Democracy, the Labor Party, and the Polish Peasant Party. The PZPR was formed in 1948 with the merger of the Polish United Workers’ Party and the Polish Socialist Party. Realizing the lack of popular support for communism and public fears of Soviet domination, the Polish communists eschewed the term communist in their official name.
In return for acknowledging the leading role of the PZPR, the two major coalition partners and three smaller Catholic associations received a fixed number of seats in the Sejm. Although one of the latter category, Znak, was technically an independent party, its allotment of five seats gave it very limited influence. Typically, the United Peasant Party held 20 to 25 percent of the Sejm seats and the Democratic Party received about 10 percent. Despite the nominal diversity of the Sejm, the noncommunist parties had little impact, and the Sejm was essentially a rubber-stamp body that enacted legislation approved by the central decision-making organs of the PZPR. Following the Soviet model, political parties and religious associations, as well as all other mass organizations, labor unions, and the press only transmitted policy and programs from the central PZPR hierarchy to Polish society.
Before I made my post #38, I did a quick search for more info about the Peasant Party. But I couldn’t find anything. Yet I knew that I once read about it. Your post clears things up. Thanks.