A relentless campaign against NRC, booth-level strategic planning by Prashant Kishor’s team and a “humble” approach to voters by state minister Rajib Banerjee brought Trinamul victories in the Kaliaganj and Karimpur Assembly bypolls on Thursday.

At least one BJP leader, Kaliaganj candidate Kamal Chandra Sarkar, conceded the party’s vow to introduce NRC in Bengal had “backfired”.

Since 1998, this is the first time Trinamul snatched the Kaliaganj seat in North Dinajpur from rivals and stepped into the hometown of late Congress veteran Priya Ranjan Das Munshi.

Trinamul retained the Karimpur seat in Nadia and increased its margin over the results of the previous Assembly election and the parliamentary polls earlier this year.

Senior Trinamul leaders in both the districts attributed the success to the hard work of Rajib, the state forest minister. This helped the party to stop the erosion in its support and galvanised leaders and workers across factions to stay united.

“It was his inclusive initiative that strengthened the party. His ability to motivate workers through direct interactions helped us surge ahead,” said a Trinamul leader in Kaliaganj.

As Rajib became the face of the Trinamul campaign, he reached out to the voters extensively. “His approach was gentle and in many places, he approached the voters with folded hands seeking support and apologising in case they had any grudge against the party or the state government. Such an approach in a campaign that was not high-pitched, but rather a bit subdued, helped him win the voters’ confidence,” a Trinamul insider said.

That Rajib’s ground work did wonders was evident from the results. In the Kaliaganj Assembly segment, the BJP had secured a lead of 56,762 votes in the Lok Sabha polls. On Thursday, Trinamul made up its loss and secured around 59,000 more votes than it had bagged in the parliamentary elections.

“A comparison of the results shows Trinamul has bled the BJP and the Left. The Left and Congress candidates had secured around 38,000 votes in the parliamentary polls but even though they had joined hands this time, the Congress candidate in Kaliaganj polled 18,857 votes,” said an observer.

In Karimpur, Trinamul strengthened its position. In the 2016 Assembly polls, Mahua Moitra had won by 15,989 votes. Moitra later contested the Lok Sabha elections — necessitating the Assembly bypoll — and secured a lead of 14,340 votes from this Assembly segment.

“Bimalendu Sinha, the Trinamul candidate, secured a lead of 23,910 votes this time and bagged over 50 per cent of the votes. This is good news for the party,” the observer said.

Rajib also devoted time in Karimpur — he is Trinamul’s observer in Nadia district. He attributed the success to “comprehensive technical planning” to highlight issues at the ground level.

“The support of PK’s team and initiatives of Mahua Moitra worked together. I just told the workers to appeal to voters with folded hands irrespective of their political affiliations to repose faith in Mamata Banerjee. This became essential after the NRC threat,” said Rajib.

BJP leaders admitted the NRC issue had acted against them. “Trinamul went on campaigning on NRC and highlighted the consequences. On the other hand, our leaders went on asserting that our party is determined to introduce it in Bengal, which is why it backfired. As a result, a section of voters did not support us this time like they had in the parliamentary polls,” said Sarkar, BJP’s Kaliaganj candidate.