LF sources said Sarkar's name was proposed by the Front's convener and MP Khagen Das in the meeting of newly elected legislators and was agreed upon unanimously.
Sarkar has been the chief minister of the north eastern state since 1998.
Later, Das along with CPI-M state party secretary Bijan Dhar met Governor D Y Patil at the Raj Bhavan and informed him that Sarkar was elected as the leader of the LF legislators.
Meanwhile, it was officially announced that the newly elected MLAs would be administered the oath of office and secrecy on March 6 at the Rajbhavan lawns here.