Comment une opposition partisane a pu s’implanter dans un jeu politique marqué par le régime de parti unique jusqu’à se faire concurrencer par des mouvements contestataires ? Aux confluents de la sociologie des partis et des mobilisations politiques, cette thèse se veut une étude de la formation de l’opposition à travers une analyse des oppositions militantes et partisanes telles que voulues et entretenues par les régimes présidentiels qui se sont succédés des années 70 à nos jours. Cette étude a montré que la formation de l’identité militante oppositionnelle est estampillée du modèle des partis politiques arrimés aux mouvements contestataires qui ont marqué la transformation du régime dès les années 80. Cette identité s’est accentuée après les années 2000 avec les transformations de l’opposition partisane concurrencée par d’autres identités qui se fraient un chemin dans le champ politique constitué des mouvements citoyen, religieux et juvénile.L’engagement des nouveaux entrants dans le champ politique aux identités multiples (citoyenne, intellectuelle et religieux) a bouleversé la donne oppositionnelle des partis politiques : Va-t-on vers un renouveau des mouvements d’opposition ou assiste-t-on à une crise de la représentation partisane de l’opposition ? Au plan théorique, ce travail plaide pour l’usage d’une approche sociologique de l’opposition pour rendre compte des logiques contestataires des acteurs partisans et non partisans qui structurent la vie politique et par ricochet les transformations des régimes présidentiels sénégalais. / How could a partisan opposition establish itself in a political game marked by the one-party regime in such a way as to be a challenge by protest movements? At The confluence of the sociology of political parties and political mobilizations, this thesis is a study of the formation of the opposition through an analysis of activist and partisan opposition, as intended and maintained by presidential regimes from the 70s to today. This study has shown that the formation of the opposition activist identity is stamped with the model of political parties tied to the protest movements that marked the transformation of the regime as of the 80s. This identity increased after 2000 transformations with partisan competition from other identities that make their way into the political arena consisting of citizens, religious and youth movements. The commitment of the new entrants into the political arena with multiple identities (civic, intellectual and religious) upset the situation of the oppositional political parties. Are we witnessing a revival of opposition movements or do we have a crisis of partisan representation of the opposition? At the theoretical level, this work advocates the use of a sociological approach to the opposition to account for the protest logic of partisan and non-partisan actors that shape the political life and as indirect result, the transformation of Senegalese presidential regimes.

The thesis focuses on influence of the AMS (Additional Member System) upon party systems of Scotland and Wales. This system is used for elections to Scottish parliament and Welsh national assembly. It was applied for the first election that was held in 1999 and it is still in use. This means AMS is used in both regions for the same time period, which allows us to compare the influence which the system has in different environment. The thesis analyzes results of all elections that were held in Scotland and Wales and defines their influence on particular parties and party systems it operates in. On the basis of these findings the general influence of AMS is formulated. Theoretical concepts by Maurice Duverger and Giovanni Sartori are used as a background for study of election systems and party systems. The position voter support and its changes are analyzed through valence theory, which uses opinion polls to explain election results. At the first sight the AMS seems to be the same one as another election system - MMP (Mixed Member Proportional). These systems are often confused or perceived as the same ones. So except the election results analysis this thesis explains also the difference between these systems and classifies them into right categories. It shows up that each of the systems belongs to...