Pinarayi Vijayan's party, the CPM, has joined the opposition to range themselves against the new law.
The ruling Left Democratic Front and opposition United Democratic Front in Kerala came together in a first today to protest against the Centre's new citizenship law, which facilitates citizenship to non-Muslims from Pakistan, Afghanistan and Bangladesh who migrated to India because of religious persecution.
Chief Minister Pinarayi Vijayan and leader of opposition Ramesh Chennithala led the protests. The two leaders shared stage at the protest venue in Thiruvananthapuram and were seen exchanging pleasantries.
Mr Vijayan's party, the CPM, has joined the opposition Congress, Lalu Yadav's Rashtriya Janata Dal and Sharad Pawar's Nationalist Congress Party to range themselves against the new law.
Senior CPM leader Sitaram Yechury has said the party would approach the Supreme Court against the law. It would also hold a mega protest against it on Thursday.
The opposition parties contend that the new law violates the Right to equality granted by the constitution, as it excludes Muslims from the three neighbouring nations from the grant of citizenship.
"Article 14 provides equality to all citizens. When a law is against the fundamental rights, it is unconstitutional... The government is silent about the Sri Lankan Tamils, thousands of Rohingyas. Even the United Nations has come out openly against this law," Mr Vijayan said at the gathering.
The Chief Minister said the present "crisis" was "deliberately created" by the Centre and the "RSS agenda was to ensure that India should not be a secular, but a religious nation".
Pointing to the unprecedented spectacle of the state's bitter political opponents joining hands in a common cause, he said, "People were worried about how we will oppose a central law. Let me make our stand clear. We all took oath under the Constitution of India... Our allegiance is to the Constitution and not to the agenda of RSS," Mr Vijayan added.
"The model before them (the RSS) is the Nazi Germany of (Adolf) Hitler. The Sangh Parivar is experimenting with Hitler's agenda. The secularism and the brotherhood of our country is threatened by igniting fake nationalism among the people," he said.