Congress spokesperson Abhishek Manu Singhvi on Saturday said his party and the Trinamool Congress must jointly oppose the Centre on issues of common interest and it would be "foolish" for both if they did not do so."There are certain issues of common interest where the Narendra Modi government must be jointly opposed."I would say it would be foolish if the Congress does not join hands with the Trinamool Congress and the Trinamool Congress would be equally foolish if they do not join hands with the Congress," Singhvi told reporters here. However, he clarified the unity of opinion to oppose the central government does not mean that the Congress would stop opposing the Trinamool at the state level."When the Chief Minister of Bengal (Mamata Banerjee) met Congress President Sonia Gandhi, there are talks on certain political issues at the Lok Sabha and Rajya Sabha level where an agreement is necessary. However, it does not mean that the intensity of confrontation at the state level would reduce even by an inch," he said.