The Bharatiya Janata Party and the Trinamul Congress will jointly contest the panchayat elections in West Bengal in May.
Trinamul supremo Mamata Banerjee had on December 14 written to West Bengal BJP president Tathagata Roy inviting the BJP to 'join hands to fight the Communist misrule'.
The BJP's state executive body has accepted the offer.
"We are happy that our alliance at the Centre is being extended to the state," Roy told reporters in Kolkata.
Trinamul has called a public meeting in the city on Monday to which BJP leaders and representatives of other National Democratic Alliance constituents have been invited.
"The formal announcement about the electoral tie-up for the panchayat polls will be made at the meeting," Trinamul leader Pankaj Bandopadhyay said.
Both BJP and Trinamul want to make the 'abysmal' financial condition of the state, the hike in power tariff and introduction of a new water tax the main issues in this election.
Neither party was willing to talk on the ticklish issue of seat adjustment. The Communist Party of India-Marxist (CPI-M) holds undisputed sway over most of the state's panchayats.