Politically, Nanjangud is in the heart of Mr Siddaramaiah's old stomping ground of Mysuru district. NDTV met him on the campaign trail where he said, "Why only Mysore - I am popular all across the state!" When asked what the results would mean for his political future and for his government he said, "This is not a referendum. No bypoll is a referendum."
But the chief minister is not popular with Srinivas Prasad, the former legislator from the seat who made this bypoll necessary by quitting the Congress after being dropped from the cabinet. He joined and is standing from the BJP.
After his exit from the ruling party, the Congress government has done a lot of work in this region. One resident of Hegadahalli village told us "A lot of work has been done here recently..." The Congress candidate, KN Keshavamurthy told NDTV that 600 crore worth of projects had been completed in the last few months.
And if the Congress is bringing in its big state-level guns to campaign, the BJP had its chief ministerial candidate, BS Yeddyurappa.
Mr Yeddyurappa, the BJP State President told NDTV, "This is definitely a run up for 2018 Assembly elections. It will send a message. We will definitely win."
The battle for Nanjangud seems to be a dress rehearsal for the big Assembly election next year.
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