Most of 2.35 million voters in Tripura are expected to cast their ballots on Thursday to decide whether the Left Front can form its seventh government - and fifth on the trot - or the Congress returns to power after 20 years.

The CPM is the dominant constituent of the Left Front that includes the CPI, Forward Bloc and Revolutionary Socialist Party. The Congress is banking on regional allies Indigenous Nationalist Party of Tripura (INPT) and National Conference of Tripura for majority in the 60-member House.

"Of the 3,041 polling stations, 32 are hypersensitive and 112 sensitive while 656 are politically vulnerable. Most of the touchy booths are in (tribal-dominated) Dhalai district and areas bordering Bangladesh," Tripura's chief electoral officer Asutosh Jindal said.

The Left Front has been on the ascendant since it took over violence-scarred Tripura in 1993. It has had a smooth run under chief minister Manik Sarkar, increasing its tally from 41 seats in 2003 to 49 in 2008.

"We tried to give our best despite geographical and fiscal constraints. We hope to carry on if the voters continue to be with us," chief minister Sarkar said.

But Tripura Congress president Sudip Roy Barman is confident that his party will turn the tide this time.