Here's your 10-point cheatsheet to this big story:
Actor-politician Shatrughan Sinha, the Trinamool Congress's candidate from Asansol Lok Sabha seat, won the bypoll with a huge margin, registering the party's first-ever electoral victory in the constituency. In the Ballygunge Assembly segment, Trinamool's Babul Supriyo, who switched from the BJP, emerged a winner.
Mamata Banerjee has thanked voters for a "decisive mandate" on both seats. She added that the party considers this to be the people's gift on the occasion of the Bengali New Year, which was celebrated yesterday.
The Lalu Prasad Yadav-led Rashtriya Janata Dal (RJD) has won Bihar's Bochahan Assembly segment with a margin of over 36,000 votes. The Congress is ahead in Chhattisgarh's Khairagarh and Maharashtra's Kolhapur Assembly seats.
Mr Sinha defeated the BJP's Agnimitra Paul, a designer-turned-MLA. The Asansol parliamentary seat fell vacant after Mr Supriyo joined the Trinamool.
The Ballygunge Assembly seat bypoll was necessitated by the death of state minister Subrata Mukherjee. The BJP has fielded Keya Ghosh while Saira Shah Halim is the CPI(M) candidate against Trinamool's Babul Supriyo.
In Chhattisgarh's Khairagarh Assembly bypoll, the ruling Congress' Yashoda Nilamber Verma is ahead by a margin of nearly 20,000 votes. The bypoll was necessitated by the death of Janta Congress Chhattisgarh (Jogi) MLA Devwrat Singh in November last year.
Chief Minister Bhupesh Baghel has said that on April 16, Congress candidate Yashoda Verma would become the MLA from Khairagarh and on April 17, a new district named Khairagarh-Chuikhadan-Gandai would become a reality.
The Bochahan assembly seat, reserved for Scheduled Caste candidates, in Bihar's Muzaffarpur district fell vacant after the death of MLA Musafir Paswan who had won on the ticket of Vikassheel Insaan Party (VIP) of Mukesh Sahani. Mr Sahani initially wanted to field the former MLA's son Amar Paswan, but the latter switched to RJD and has now won.
Mukesh Sahani later fielded Gita Devi who finished a distant third. The BJP's Baby Kumari, who had defeated heavyweight candidate Ramai Ram in 2015, finished second by a margin of over 36,000 votes.
In the Kolhapur North assembly constituency of western Maharashtra, Congress' Jayashree Jadhav is leading by over 18,000 votes. The BJP's Satyajit Kadam is in the second position.
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