Referring to a closure report filed by the Special Police Establishment, which works under the Lokayukta, last December absolving the CM of the charge of misusing his official position, Singh said,"there was enough evidence against Chouhan in the case but still the Lokayukta had decided to close it".
A court had given a clean chit to Chouhan in the 'dumper' scam in which he was accused of misusing his official position to rent out dumper trucks to an industrial house as a quid pro quo for allotting a mining lease.
Singh said Congress would challenge the closure report of Lokayukta in the Madhya Pradesh High Court.
The 'dumper scam', as the Opposition called it, had troubled Chouhan and his wife Sadhna Singh, in whose name the dumpers were purchased, with him maintaining that no irregularities were committed. The case had been registered against Chouhan and his wife in November 2007.
Referring to the recent victory of Congress in Harda municipal corporation election, Singh said the "countdown" for BJP has begun in the state.
Taking a dig at Team Anna, the former chief minister said, "when political parties talk of widening their base they are said to be indulging in politics of vote bank, but when Anna Hazare does the same for his team not a single word is said".
Singh also appealed Hazare to clear his stand on the reported statement of MNS chief Raj Thackeray that north Indians should quit Mumbai.