He submitted his resignation to Speaker Ramendra Debnath and later told reporters that he had resigned as MLA but refused to tell the reason.
"The decision is personal. I will not say anything more," Sarkar, also a former Speaker, said.
Sarkar had yesterday said that he was asked by "some influential" Trinamool Congress (TMC) leaders of the state to join their party but he had declined.
With Sarkar's resignation, the Congress' strength in Tripura Assembly has been reduced to nine from 10 in the 60-member House where the strength of ruling Left Front is 50.
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Meanwhile, Congress leader Sudip Roy Burman, who had resigned from the post of Leader of Opposition over the issue of Congress-Left alliance, is likely to write to the Speaker tomorrow that he, along with five other MLAs, had joined TMC, sources close to him told PTI.
The dissident group led by Roy Burman now needs altogether six legislators to evade the provisions of anti-defection law.