By Zubair Ahmed
BBC News, Mumbai
The Hindu nationalist Shiv Sena party has suffered losses in two elections in Maharashtra state. Both seats were won by the Congress party.
The Shiv Sena was split in July when Narain Rane was expelled
One by-election was for a seat in the national parliament, the other was for the Maharashtra assembly.
The ruling Congress party's Narain Rane and Priya Dutt, who has just stepped into politics, won the seats.
Analysts say the defeats may lead to further cracks in Shiv Sena, led by Bal Thackeray.
The alliance of the Congress party and the National Congress party beat an alliance of the Shiv Sena and the Bharatiya Janata Party in the state elections in 2004.
Congress party's Narain Rane, who was expelled from the Shiv Sena in July, won the state assembly seat for the constituency of Malvan.
Meanwhile, newcomer to politics, Priya Dutt, who is the daughter of the late film star-turned-politician Sunil Dutt, was elected to the Mumbai (Bombay) north-west parliamentary constituency.
Voters resent the Thackeray family's hold on Shiv Sena
The seat fell vacant when Mr Dutt, who was the federal sports minister, died in May this year.
But even though the results of these by-polls were a foregone conclusion, the repercussions are yet to be felt.
Experts say these two results have dealt a heavy blow to the Shiv Sena and may lead to further break-up of the party.
In July, when Narain Rane was expelled from the party, he took hundreds of Sena workers into the Congress fold, resulting in the party splitting.
He also persuaded three members of the Legislative Assembly (MLAs) to join the Congress party with him.
Experts believe, after this victory he is gearing up to invite more Sena MLAs to join the Congress.
But it is too early to write the Shiv Sena's obituary, says Kumar Ketkar, the editor of a leading Hindi newspaper.
He believes traditional Shiv Sena voters have not rejected the party's right-wing Hindu ideology, but they have rejected the Thackeray family's hold over the party and their style of functioning, which, he argues, borders on dictatorship.
A victorious Mr Rane has asked the party chief Bal Thackeray to resign.
There were no comments from the Shiv Sena.