Agartala, June 22 : The last-minute preparations were underway on Wednesday for the politically crucial by-elections in four assembly constituencies in Tripura, scheduled to be held on Thursday. Central and state security forces were deployed ahead of the vital by-elections being termed as 'semi-final' before the 60-member Tripura assembly's general elections which are around 8 months away. As the BJP, CPI-M-led Left Front, Congress and the Trinamool Congress and other local parties put up their candidates, the by-polls would be multi-cornered. The prohibitory orders under section 144 CrPc have been promulgated in the four assembly constituencies -- Agartala, Town Bordowali, Surma, Jubarajnagar in three districts -- West Tripura, North Tripura and Dhalai district. In all, 1,89,032 voters would decide the political fortune of 22 candidates of the BJP, CPI-M-led Left Front, Congress and the Trinamool Congress, and other local parties. The over-a-month-long hectic poll campaign for the four assembly seats in Tripura ended on Tuesday while a tense situation prevailed in some areas of these poll-bound constituencies. The campaign was marred by violent incidents. Former BJP minister Sudip Roy Barman, who is now contesting from the Agartala constituency on a Congress ticket, was injured when "BJP activists" allegedly attacked him late on Sunday night. Barman, a five-time MLA from the politically crucial Agartala constituency, is now under treatment at a private hospital in Agartala. The focus of the by-elections was on the Town Bordowali Assembly constituency, where 69-year-old Congress-turned-BJP leader and Chief Minister Manik Saha is contesting against five other candidates. Saha, the state party president and a Rajya Sabha member who assumed office on May 15, a day after Biplab Kumar Deb's resignation from the top post, is contesting the elections for the first time. To fulfil the constitutional bindings, he has to become a member of the Assembly within six months. The by-polls were necessitated after the resignation of three BJP MLAs and the death of CPI-M legislator Ramendra Chandra Debnath. Amid open resentment among a section of BJP legislators against the then Chief Minister Deb, three MLAs -- Sudip Roy Barman (Agartala), Ashish Kumar Saha (Town Bordowali) and Ashis Das (Surma) -- quit the BJP and the Assembly. Roy Barman, also a former BJP minister, and Saha joined the Congress in February this year while Das joined the TMC last year. Das last month also resigned from the TMC. Elected from the Jubarajnagar constituency six times, Debnath was Assembly Speaker multiple times. He passed away on February 2 in Kolkata due to kidney failure. The votes will be counted on June 26. /IANS