Asserting that the electoral battle would be fought in a three-cornered contest among Congress-led UPA, BJP-led NDA and the non-Congress, non-BJP combination, Left sources said these 12 parties would pool their strength from their respective states for an all-India combination.
Apart from the four Left parties, the others in this combination are JD(U), BJD, AIADMK, JD(S), Samajwadi Party, Asom Gana Parishad, Jharkhand Vikas Morcha (Prajatantrik) and Manpreet Singh Badal's People's Party of Punjab.
Some more parties could join the combination soon, the sources said, adding that these parties had formed a block to jointly raise specific issues in Parliament during the last session.
At tomorrow's meeting, the parties are likely to come out with a broad outline of political positions and policies against Congress and BJP and decide on how to strengthen efforts of the constituent political parties in the elections in their respective states.