Indians are living in a climate of hate and intolerance, Kerala Chief Minister Pinarayi Vijayan says, adding that the Congress was incapable of fighting "communal forces" ideologically.
Vijayan also said that the Communist Party of India-Marxist (CPI-M) will decide whether he has to exit Kerala and play a larger national role.
"The RSS-BJP combine has aggressively intensified its communal Hindutva campaign since it assumed power in Delhi," Vijayan told this correspondent in an email interview .
"People of the largest democratic country are living in a climate of hate and intolerance. These forces are trying to eliminate or crush any voice of dissent. If you dare to oppose the communal offensive, you will be depicted as anti-national.
"In BJP-ruled states, police forces violently attack protestors when they raise their voice against the Saffron Brigade," he added.
Vijayan recalled the murders of doctor-cum-rationalist Narendra Dabholkar, CPI leader and rationalist Govind Pansare and former Kannada University Vice Chancellor and rationalist M.K. Kalburgi.
"All of them were vociferous in their opposition to superstition, obscurantism and the perpetuation of the communal agenda by the rightwing Hindutva forces," the CPI-M leader said.
"Recently, Gowri Lankesh, an eminent journalist, was also shot dead in Bangaluru for the same reasons. What is more worrying is that while the whole nation was angry about the cold-blooded murder, a section of people celebrated her death on the social media.
"We remember that RSS people had distributed sweets when Mahatma Gandhi was shot dead in 1948," he added.
Vijayan said the Bharatiya Janata Party (BJP) and its ideological mentor, the Rashtriya Swayamsevak Sangh (RSS), were "working overtime to build an anti-Left alliance of all communal forces".
He added: "(But) the Congress is incapable of fighting the communal forces ideologically.
"In fact, the RSS-BJP combine is working overtime to build an anti-Left alliance of all communal forces. Needless to say, for the RSS and BJP, the Congress party is not an opponent politically."
Vijayan claimed that only the Left parties could check Hindutva.
He said there were more and more attacks on Left cadres because the Hindutwa forces feared the rise of Left parties.
"It is an undisputed fact that only Left forces are consistently and firmly opposing the Hindutva agenda of RSS and BJP," he wrote in his reply.
"The CPI-M is in the forefront in the fight against communal-divisive forces. Resultantly, the BJP-RSS have intensified their campaign against Left in general and the CPI-M in particular.
"The Left is specially targeted as they consider it their main ideological adversary and biggest challenge to their project of converting India into a 'Hindu Rashtra'."
Denying charges that his party was involved in the killings of RSS and BJP workers in his home district Kannur, Vijayan said many more CPI-M members were being killed in Kerala.
"Since the LDF government assumed office in Kerala in 2016, RSS has intensified its violent attacks against CPI-M cadres. At the same time, playing victim, the RSS and BJP have launched a massive misinformation campaign using all the clout in the central government."
Vijayan said it was for the CPI-M to decide whether he must play a larger national role in politics.
The 22nd CPI-M Congress due to take place in Hyderabad in April will chalk out a new political strategy.
"With regard to my role in national politics, unlike the Congress and many other parties, the CPI-M has a collective leadership," he said.
"We chalk out and implement our policies democratically and collectively. The CPI-M feels that all secular and democratic forces should come together in the fight against Hindutva forces. However, it should not be construed as an electoral alliance or understanding."