The Left had not only failed to help the states which they ruled to march ahead but "they also try to give garb of ideology to political opportunism", Singh said, taking on the communist parties in the LDF-ruled Kerala at an election meeting here.
"It is unfortunate that the Left Front refuses to change with time. The result is that they pursue policies and programmes that are not relevant to time", Singh said.
"When I came during the Lok Sabha polls I had said that our Left friends are on the wrong side of history. I reiterate that", he said in his first campaign meeting for the April 13 Kerala Assembly polls.
Singh said everybody was aware of the "damage" done to West Bengal by the Left Front by their more than three decades rule and they also failed to take Kerala forward.
"Under the LDF rule your state (Kerala) has not progressed as much as it could have and should have." While the interests of the common man were neglected under the Left rule, CPI(M) party workers gained at the cost of ordinary people, Singh said.
He said due to the "wrong" policies of the LDF, the state had failed to attract any private projects as the entrepreneurship had been discouraged and failed to create a climate conducive for investment.
Singh also attacked the LDF rule for failing to take proper advantage of the central schemes despite the UPA at the Centre extending all support for Kerala in every sector.