Why are West Bengal by-elections important for Mamata Banerjee?

Mamata Banarjee is not ready to accept her defeat from BJP's Suvendu Adhikari in West Bengal's Nandigram. From recounting of votes to moving to Kolkata High Court, West Bengal CM has done it all. Now, to protect her position in the state, Mamata Banarjee is eyeing on by-election. Meanwhile, Suvendu Adhikari has moved to Supreme Court