1995: BJP got 65 MLAs. SS got 73. So BJP gave CM post to Shiv Sena.
1999: BJP-SS lost. But since SS had more MLAs, BJP gave Opposition Leader post to SS.
2004: Same as 1999. BJP-SS lose. SS was given LoP post by BJP in the alliance.
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2) BJP - SS Alliance history:
2009: BJP-SS lost. BJP gets LoP, as it had 45 MLAs v/s SS's 44.
2014: BJP and SS fought separately, but BJP got CM post as it had 123 v/s SS's 63.
2019: BJP wins 105 out of 150 contested, while SS won just 56 out of 124 contested.
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3) BJP - Shiv Sena Alliance history:
Clearly 2019 was BJP's turn again to get CM post for the full term looking at the alliance dharma since 1990s. You can judge from the history here, as to who got greedy here for a dynasty, and dumped this precious NDA alliance.