Congress general secretary and chief spokesperson Randeep Surjewala said there is a difference between political opportunism and the fight for the truth, which the Congress is fighting and parties should understand this.
"You cannot by sheer political opportunism proceed to strengthen the very fascist forces, represented by the RSS and the BJP, that you are pretending to fight," he told reporters.
"Political opportunism may be good for some people or parties, but for us Indianness and our country, democracy and brotherhood, and our compassion and article of faith are the ones on which the Congress has never compromised," Surjewala said.
The Congress leader also accused Trinamool Congress (TMC) leader Banerjee of speaking different languages at different times, and recalled how she had sided with the BJP and switched sides between the United Progressive Alliance and the National Democratic Alliance several times in the past.
"For her it can be political expediency, but for us fighting the BJP and the RSS is close to us," he said.
Surjewala recalled Banerjee's statement on August 20 that all political forces have to come together to save democracy in the country and it would not be possible when one stands in support of the BJP.
The Congress leader hit out at the TMC for fighting against the Congress in Goa and Uttarakhand. The assembly polls in these states are slated early next year.
The Congress is large-hearted and sacrifices to take other parties along with it, Surejwala said, adding that political parties should think if they are not supporting Prime Minister Narendra Modi with their actions.
"Is Mamata not doing the same as Modi ji is doing. Modi ji is buying legislators and so is Mamata ji. Modi ji is breaking parties and so is Mamata ji doing in breaking parties. The inspiration that Mamata ji once had from Indira Gandhi and Rajiv Gandhi, it seems she has made fascism her inspiration now. Hope she has not taken on the same path," Surjewala asked.
With PTI inputs.