Congress chief spokesman Randeep Surjewala told reporters that Mani has resigned in the highest tradition of democracy, despite no guilt having been proved in the case against him.
"Will Prime Minister Narendra Modi implement the same yardstick in the case of Shivraj Singh Chauhan in the wake of two cases in the Vyapam scam and Vasundhara Raje and Sushma Swaraj in the Lalit Modi controversy?" Surjewala asked.
Surjewala asked whether Modi would use the same yardstick to remove Chhattisgarh Chief Minister Raman Singh in the wake of the PDS scam and Maharashtra Ministers Pankaja Munde and Vinod Tawde who have been "accused in many scams".
The monsoon session of Parliament was a virtual washout this year with the Congress pressing for the resignations of Swaraj, Raje and Chauhan.
The winter session of Parliament is scheduled to commence from November 26.