Bangalore: Voters in eight assembly constituencies of Karnataka will cast their ballots on Saturday in a by-election that could impact the stability of the ruling Bharatiya Janata Party, or BJP, government in the southern state.

Seven of these constituencies—Arabhavi, Hukkeri, Karwar, Deodurg, Turuvekere, Madhugiri and Doddaballapura—are going to polls because the sitting legislators resigned to join the BJP. Of these, four belonged to the Janata Dal (Secular), or JD(S), and three to the Congress party. The eighth seat, Maddur, fell vacant following the death of JD(S) legislator M.S. Siddaraju.

Second chance: Karnataka chief minister B.S. Yeddyurappa. The BJP needs to win three of the eight seats to get a simple majority of 113. Hemant Mishra / Mint

V. Dhananjay Kumar, BJP spokesman for Karnataka, said the results of polls elsewhere would not have any impact in the state.

“These are mostly localized elections," Kumar said.

The BJP needs to win three of the eight seats to get a simple majority of 113 in the 224-member state legislative assembly where it currently relies on the support of six independents. Five of them are ministers in chief minister B.S. Yeddyurappa’s cabinet. Currently, the BJP has 110 seats.

Analysts say the by-election could be equally critical for the JD(S), a party led by former prime minister H.D. Deve Gowda, which has lost five seats in the assembly since state elections in May—either due to defection or death.

The party’s strength in the assembly has fallen to 23 after the polls in 2008, compared with 58 in 2004.

“If the JD(S) has to stay (relevant) in Karnataka in the future, these elections become absolutely crucial," said P.L. Dharma, head of the political science department at Mangalore University.

The party is fielding Gowda’s daughter-in-law Anita Kumaraswamy as its candidate in the by-election for the Madhugiri seat where the BJP candidate is a former JD(S) loyalist, C. Chennigappa.

In an earlier interview, JD(S) party spokesman Y.S.V. Datta had said his party was confident of winning back five seats.

“It (elections) will have a bearing on the JD(S)’s national ambition," said K. Sathyanarayana, a Bangalore-based political commentator. “If it is wiped out, it loses its credibility."

The JD(S), a former coalition partner of the Congress in Karnataka, is part of an effort led by the Left parties to form a third front to counter the national alliances of the Congress and the BJP in parliamentary polls due next year.

The results of the bypolls will be announced on 30 December.