1. Their own organisational weaknesses,
2. They were Prisoners of the policies imposed by Stalin on International Communist Movement,
3. In backward and Colonial countries Stalin decreed, the movement had to go in two stages-democracy and then socialism.
In Russia these had actually been the policy of the Mensheviks. But in India the Progressive National Bourgeoisie was a myth. They proposed to build up a Popular Front.
Now, the foundation of Communist Party has two records. i) 26 Dec 1925, ii)Oct 1920, in Tashkent, USSR. But during 2os and 30s the party was badly organised and actuallywas divided in so many groups.The British Colonial authorities also had banned all sorts of activities of he communist Party upto 30s.Only in 1935 the party could function. Even then they could not function within the minority groups.
The CPI failed to inspire and mobilise the people and play an effective role for two reasons,
i) CPI did not extend the national question to properly embrace the various national minorities other than the Muslim minority.
ii) CPI depende too much , almost entirely, on Congress_League unity as the outcome of the national minority questionand thereby left that questionin real terms in the hands of those who were already divided quite decisively as communal Parties of the upper and middle class Hindu and Muslim communities respectively.
Thus they failed to inspire the religious,ethnic,lingustic and other minorities, as well asthe scheduled castesamong the Hindus, in identifying their specific interests and to fight for them within the framework of their struggle for Independnce.They wer eager to unite the hands of Ganhdhi and Jinnah.
It should be mentioned here that in the 2nd conference of the CPI in 1948, they were geatly influenced by the Congress and identified Nehru as the embodiment democratic movement in India.
Moreover they had withdrawn the Tebhaga movement of the peasants of Bengal inNov 1947.