The SP had earlier sought a couple of seats from the Front, but decided to go it alone after being rebuffed.
The move, which comes days after the LF announced its candidates for the 42 seats from the state, may also ruin the Left's endeavour to secure a non-Congress and non-BJP alliance.
Earlier representatives of a host of Left and regional parties, including the likes of SP chief Mulayam Singh Yadav and CPI-M general Secretary Prakash Karat, held a meeting to give shape to the Third Front.
Mitra noted that the Third Front was not an alliance, but rather a joint commitment by the parties to dethrone the Congress led-UPA and prevent the BJP spearheaded NDA from coming to power.
CPI-M leader Mohammad Salim, however, felt the move will not have any adverse effect on the Front's electoral fortunes and accused the ruling Trinamool Congress of engineering the break-up.
