Jonathone Sangma, along with his personal security officer and two NCP party workers, was killed at Williamnagar on Sunday night after an Improvised Explosive Device went off near his convoy in East Garo Hills district. His death has sent shock waves across the state.
Following the killing, the election in Williamnagar constituency, where Mr Sangma was a candidate, has been countermanded as per norms.
"The case related to the murder should be handed over to the NIA for investigation,'' NCP state working president Vijay Raj told reporters in Shillong.
He said a complaint was also lodged with the Chief Electoral Officer F R Kharkongor demanding adequate security to all NCP candidates.
The party had fielded 21 candidates, including Jonathone Sangma for the February 27 poll to the 60-member assembly.
The NCP leader alleged that the state machinery had failed to protect the people, resulting in the ''dastardly and fatal attack'' on Sunday night.
The Meghalaya election office sought 10 more companies of the Central Armed Police Forces for the Garo Hills region following Mr Sangma's death.
Chief Minister Mukul Sangma tweeted that the perpetrators of the crime would be brought to book.
The BJP, echoing the NCP, said the law and order situation in the state had failed and sought increased deployment of central security forces so that vulnerable segments of voters in the state were protected from any threat.
''The BJP notes with great concern the unprecedented and first (incident) in the history of the state's electoral politics the blatant use of violence to eliminate a political leader,'' BJP spokesperson Nalin Kohli told journalists in Shillong.
"It was a close shave for his (Sangma's) wife and son as he had dropped them first, before proceeding to his next meeting,'' Mr Kohli said.
Expressing concern over the violence in Meghalaya, specially in the Garo Hills region, he said, ''Not only is this unacceptable but also an indication of the total collapse of the law and order claim of the Congress government.''
The authorities must come clear on if the attack on Mr Sangma was an attempt to vitiate the electoral process or if there was any intelligence breakdown or motivated by a political party, he said.
The BJP leader demanded that central security forces be increased to ensure that vulnerable segment of voters in the Garo Hills were protected from any threat of violence.
''Our clear assessment is that the law and order is not being monitored in the right manner by the state agencies,'' he claimed.
Other parties too condemned the killing.
The Hills State Peoples' Democratic Party demanded a thorough investigation into the incident.
''The incident has created a fear psychosis among the people of the state in general and Williamnagar in particular,'' HSPDP leader Londoner Sohtun said in a statement.
United Democratic Party leader B M Lanong termed the incident as ''cowardly'' and said, 'the attack is aimed at vitiating the election process. Such an incident is shocking and uncalled for in a state like Meghalaya.''
National People's Party president Conrad K Sangma in his tweet last night condoled Jonathone Sangma's death.
Official sources have remained tightlipped about the killing.
According to an NCP worker, who was with the candidate last night, the incident took place when they were returning from Sawilgre village in Samanda block of East Garo Hills district.
The candidate and his men had first visited Jongmegre as the people there had called Mr Sagma. They then went to Dorakgre where they heard that posters were put up threatening people against voting for him.
''We assured the people not to be afraid and vote freely,'' said the eye witness.
The team then went to Sawilgre as the villagers had asked them to. However, when they got there, there was no one in the meeting place and the chairs were lying empty. After waiting for some time the team left in the four vehicles they had come in.
''I was in the last vehicle and the blast was in a vehicle ahead. There were seven people in that vehicle. After the blast we all lay on the ground waiting for gun fire, which, however, did not happen. We then rushed to the candidate's vehicle and tried to call back the pilot car but it had gone,'' he said.
NCP supporters, who were with the candidate, called the police and the blast victims were taken to Williamnagar civil hospital, he said adding that Mr Sagma along with three others had succumbed to injuries on the spot.