According to the police, Haralal Debnath - who ran a grocery - was killed on Friday night at Habibpur under Ranaghat police station.
The victim's wife Chandana Debnath said two assailants came to the shop and asked for some goods, and fled after firing at Haralal when he was busy getting the grocery items for them.
A police officer said investigation was on to find the culprits and the motive for the crime.
Ranaghat MP Jagannath Sarkar told IANS that Debnath was actively involved with the BJP since 1996.
"Since 1996, he was a member of our akhanda mandal committee of Ranaghat. After that, due to pressure put on him, he had kept aloof for some time, but again actively campaigned for our party in the recent lok Sabha polls," said Sarkar.
He said it was a clear case of political murder. "The Trinamool Congress is responsible for the killing".
Sarkar also alleged that the deceased's wife was threatened by miscreants to keep her mouth shut about the incident.
"The Trinamool is responsible for the killing. Let there be a proper investigation and the truth will come out," he said.
The Trinmaool has, however, denied any connection with the crime and claimed that the victim had no recent links with the BJP.