Amid chaos over CAA, as Prime Minister Narendra Modi prepared for his two-day visit to West Bengal on Saturday, the person he missed sorely was his teacher Swami Atmasthanandaji.

"I am excited to be in West Bengal today and tomorrow. I am delighted to be spending time at the Ramakrishna Mission and that too when we mark Swami Vivekananda's Jayanti. There is something special about that place," the Prime Minister tweeted.

And added: "Yet, there will be a void too! 

"The person who taught me the noble principle of ‘Jan Seva Hi Prabhu Seva', the venerable Swami Atmasthananda Ji will not be there. It is unimaginable to be at the Ramakrishna Mission and not have his august presence!"

During his nearly 20-hour trip he will dedicate four renovated heritage buildings to the nation besides inaugurating the sesquicentenary celebrations of Kolkata Port.

He is also scheduled to launch an interactive light and sound show of Rabindra Setu (Howrah Bridge) and go to the Belur Math -- global headquarters of the Ramakrishna Math and Ramakrishna Mission -- on his first visit to the state after the Lok Sabha polls.

Stringent security has been put in place for the Prime Minister's tour amid security forces' apprehensions that a couple of organisations could try to organise large-scale protests, including black flag demonstrations, at the NSCBI Airport and on the streets.

A social media campaign has been going on with the hashtag #GoBAckModi, asking people to rally at the airport and also on VIP Road to prevent the Prime Minister from entering the city.

Rajya Sabha MP Swapan Dasgupta had articulated such fears when he spoke of a "conspiracy" to scuttle Modi's tour while interacting with the media on Thursday.

"A conspiracy is on on social media not to allow the Prime Minister to come out of the airport," he had said, alleging that a minister -- whom he did not name -- was also involved in the plan.

"This is also being talked about in the student community to gather maximum people. People should be aware of this conspiracy," Dasgupta had said.

Assuring that security for the Prime Minister would be foolproof, officials said the entire route from the airport to the city would be "sanitised", including installation of barricades on the roads to ward off any chance of protest.

Meanwhile, the CPI-M has asked people to update their display picture on WhattsApp and Facebook with #GoBackModi frame "and strengthen the movement against CAA, NPR (National Population Register) and NRC (National Register of Citizens)".

In a statement, Left Front Chairman Biman Bose has urged 17 Left parties, Congress and other outfits to show black flags to Modi and organise demonstrations in various areas of the city and district headquarters with the slogan "Narendra Modi go back".

The Left-backed Students Against Fascism has called for gatherings in five places in the city, including central Kolkata's Esplanade.

As per the itinerary, Modi would fly in to the city at 5 p.m. on Saturday and head straight for the renovated and refurbished Old Currency building, one of the four heritage structures he would dedicate to the nation.

The three other buildings are Belvedere House, Metcalfe House and Victoria Memorial Hall.

Modi would then proceed to the Millennium Park on the bank of Ganga and inaugurate the interactive light and sound show of Rabindra Setu, before concluding his day's engagements with an hour-long trip to Belur Math.

The Prime Minister would spend the night at Raj Bhavan where Governor Jagdeep Dhankhar has organised a dinner in his honour.

On Sunday, the Prime Minister would inaugurate the sesquicentenary celebrations of Kolkata Port at the Netaji Indoor Stadium before departing the city by an Indian Air Force flight at 12.45 p.m.