In this article, the author presents in detail the position of the main political parties regarding the constitutional issue of the Romanian Kingdom united in 1918 and the political controversies between these, on the topic of legitimacy of the party entitled to submit to the Parliament a draft of constitution, which would enshrine the new political realities of the Romanian state, following the union of the old Romanian provinces with the Romanian Kingdom at the end of the First World War. As it is well known, during the period 1919-1922 several preliminary drafts of constitution were drawn up, which gave rise to lively public and parliamentary debates, in which it took part, especially, the National Liberal Party, the National Party of Transylvania1 and the Peasants' Party, each of them considering themselves entitled to promote their own preliminary draft of constitution, which attracted the categorical rejection of the others. Although the political controversies between the political parties had as their object the preliminary drafts of constitution, the real adversity between the parties started from their different visions regarding the future development, as a country project, of Romania, the Liberal Party continuing to promote the idea of an administration based on the principle of centralization and on the authority of the central government, while the National Party was more attracted to the idea of a provincial autonomy. The author does not consider that the principles of the constitutional democracy and of the European-style parliamentarism, borrowed in 1866 and revived in 1917 and 1923, were „compatible", in the interwar period, with an electoral system corrupted even by the actions of the Crown and with an executive strengthened and personalized by the authority of the prime minister. The author analyzes the content of the preliminary drafts of constitution elaborated in the era and concludes that the political parties of that time failed to overcome the system limits of the naive parliamentarism existing at that time. Although the legitimate unification of the country through the sovereign acts of union of the old Romanian provinces with the Romanian Kingdom did not surprise the political class, neither the Parliament, nor the governments that came to power immediately after 1918, neither King Ferdinand, nor the leaders of the political parties knew or were able to face the economic, social, national and political challenges of the Great Union and to offer constitutional and legislative solutions to overcome them. Therefore, invoking as well the constitutional provisions from 1923 as a source of reflection for the constitutional thinking from 1991 is not completely unjustified. [ABSTRACT FROM AUTHOR]