Especially kerala, where all the regional parties join hands either with the congress to form UDF or the communists to form the LDF. In kerala the speciality is that no party stands alone in the elections, they all hae front, as regards tamilnadu, the power is shared by two opposite forces the DMK and the AIADMK, all the other parties just hold on to the pallu of these main parties. westbengal, is a different story, where the communist parties have a strong presence, just now interuppted by the TMC now
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It goes with the self centred attitudes mostly prevailing in these states. Almost they are country within country. U study any big country, there are few states like that. Even today, Texas has a different culture and they try to maintain their original identity. Most of the states in USSR too was like that. Tibet and Xinjiang in China, northern province of Italy, Najran and Hail region in Saudi, ................ Few of them want to maintain their original identity untouched but want to be part of federal but few want a separate country. Fortunately three states in ur Q belongs to first category.