The three state assemblies have a strength of 60 members each.
The desertion by more than two-thirds of the Congress legislative party makes TMC, a newbie in Meghalaya, the principal opposition in the Northeastern state.
A coalition government, led by National People's Party leader and outgoing chief minister Conrad Sangma, will be sworn-in on Tuesday morning in Meghalaya, while an all-party government, led by Nationalist Democratic Progressive Party (NDDP's) Neiphiu Rio will take oath later in the day in Nagaland.
One of the significant outcomes of the Meghalaya assembly polls is the end of one political dynasty in the state and the rise of another.
'Discussions are on' within the saffron camp, and a final decision on whether to come out of the ruling coalition or not will be taken in one month, he claimed.
The 36 villages cover a 36.9 sq km area, while the 30 villages are spread over 18 sq km area, he said.
Prime Minister Narendra Modi and Home Minister Amit attended the swearing in ceremony as did BJP president J P Nadda.
Six non-Congress parties and an independent MLA constitute the MDA government.
Stakes are high for the Bharatiya Janata Party ahead of the counting of votes on Thursday for three state assembly polls, as the results will signal if it has deepened its roots in Tripura, a Left bastion captured by the party in 2018, and made further inroads in Meghalaya and Nagaland, or if the opposition has managed to dent its influence.
Ruling parties held sway in most of the 13 states in the assembly byelection results declared on Saturday, with the Bharatiya Janata Party and its allies wresting seats in Uttar Pradesh, Bihar and Rajasthan and the Trinamool Congress sweeping West Bengal.
The NPP has won six seats and was leading in 19 other constituencies as counting of votes polled in the February 27 polls was underway.
This will be the 49-year-old JMM leader's fourth stint as chief minister. Soren retained the Barhait seat, defeating BJP's Gamliyel Hembrom by a margin of 39,791 votes in the recent assembly polls.
The counting of votes for the bypolls to 46 assembly seats in 13 states and in the Lok Sabha segments of Nanded in Maharashtra and Wayanad in Kerala, a crucial electoral exercise since the parliamentary polls in April-May, will begin at 8 am on Saturday.
People lined up at polling booths well before voting began at 7 am on Monday. Sources said that there was a voter turnout of 75 per cent. The fate of 331 candidates from different political parties, including six former chief ministers of the state -- D D Lapang, Purno A Sangma, Salseng C Marak, E K Mawlong, F A Khonglam and J D Rymbai were sealed in ballot boxes.
A high-level committee on Thursday recommended simultaneous elections for Lok Sabha and state assemblies as the first step followed by synchronised local body polls within 100 days.
Conrad Sangma on Friday evening submitted the letter of support to Meghalaya Governor Phagu Chauhan at Raj Bhawan signed by 32 MLAs of NPP, BJP, Hill State People's Democratic Party and two Independents.
National People's Party (NPP) president Conrad K Sangma on Monday said his party will have eight ministers in the next Meghalaya government headed by him, while its allies will get four ministerial berths.
The Nationalist Congress Party (NCP) general secretary and former Lok Sabha Speaker Purno A Sangma has fielded both his sons in the March 3 Meghalaya Assembly elections from two constituencies in his strong bastion in Garo Hills areas of the hill state.
"You will not see him (PM) hug a poor person," Gandhi said.
The first election that the US and UK-trained Conrad Sangma, who now runs the National People's Party (NPP) formed by his father PA Sangma, fought in 2004 had resulted in a narrow defeat.
Sarma said no NDA partner will enter into any alliance with either Congress or the Trinamool Congress after the results are declared on Thursday.
The constitution of a committee by the Centre to explore the feasibility of "one nation, one election" has opened up the possibility of Lok Sabha polls being advanced so that they could be held with a string of state assembly polls.
The bypolls were conducted for two Assembly seats in Uttar Pradesh, one each in Meghalaya and Odisha and the Jalandhar Lok Sabha constituency in Punjab.
Congress MP Rahul Gandhi will embark on a fresh padayatra (foot march) from Gujarat to Meghalaya and during that period leaders and workers of the party's Maharashtra unit would criss-cross the state, Maharashtra Pradesh Congress Committee president Nana Patole said on Tuesday.
They will, however, remain in the Congress, Congress Legislature Party (CLP) leader Ampareen Lyngdoh said.
Amid opposition unity talks, Congress leader Rahul Gandhi on Wednesday attacked the Trinamool Congress, alleging that it was fighting elections in Meghalaya to ensure the Bharatiya Janata Party comes to power in the state, drawing a sharp reaction from the Mamata Banerjee-led party.
Prime Minister Narendra Modi, his cabinet colleagues Amit Shah, Nitin Gadkari, Rajnath Singh, chief ministers of Nationalist Democratic Alliance-ruled states and prominent personalities from industry and Bollywood on Thursday attended the grand swearing-in of Devendra Fadnavis as Maharashtra Chief Minister in Mumbai.
Nagaland Chief Electoral Officer Abhijit Sinha said the violence in Akuluto constituency in Zunheboto district left one dead and two injured.
Over 83 per cent of the more than 13 lakh electorate cast their vote on Monday in the single-day Nagaland state election which passed off by and large peacefully, Chief Electoral Officer V Shashank Shekhar said.
Exit polls by various channels predicted a hung house in Meghalaya, a win for the NDPP backed by the BJP in Nagaland, the two states that went to polls on Monday, and seemed to oscillate between predicting a clean sweep for the BJP to a hung house in the state of Tripura, where a new party the Tipra Motha may emerge as a potential king-maker in the polls, held a week back.
The development is a major boost for West Bengal Chief Minister and TMC supremo Mamata Banerjee, who has been trying to expand her party's footprint beyond her native state.
West Bengal Chief Minister Mamata Banerjee on Tuesday said she has written to the Centre, seeking permission to visit the strife-torn state of Manipur.
A habeas corpus petition was mentioned before a bench of Chief Justice Manmohan and Justice Tushar Rao Gedela for listing on October 3 by a lawyer for Wangchuk's "next friend".
The Union Cabinet on Wednesday approved the proposal for 'one nation, one Election' as recommended by the Kovind panel, Union minister Ashwini Vaishnaw said on Wednesday.
BJP Meghalaya in-charge Chuba Ao said the party's 'Congress mukt campaign' is valid for the state and hence the party will seek clarification from the chief minister.
Hours before the ceremony, Saini visited the Valmiki Bhawan and offered prayers at a gurdwara and the Mansa Devi temple in Panchkula.
CM Sangma, introducing the resolution, alleged that the notification was "designed to affect" the people of the north-east in general and Meghalaya in particular.
Sangma said finding the solution was not an easy decision, but for the political will of Prime Minister Narendra Modi and Home Minister Amit Shah.
Bypolls to one Lok Sabha and four assembly seats across four states will be held on May 10 along with the Karnataka assembly polls, the Election Commission announced on Wednesday.
Jonathone N Sangma was on his way to constituency when the convoy came under attack.