New Delhi, Oct 26 Former Prime Minister Manmohan Singh on Friday criticised his successor for failing the electorate and "vitiating" the environment of national institutions such as the CBI and universities.Speaking at the release of a book on Prime Minister Narendra Modi, titled 'The Paradoxical Prime Minister: Narendra Modi and His India' by Congress leader Shashi Tharoor, Singh said the "idea of India" is under threat under Modi and that voters' faith in his words and promises has eroded."The government he (Modi) presides over has been mostly silent in the face of widespread communal violence, mob lynching, and cow vigilantism ... the environment of our universities and national institutions like teh CBI has been vitiated," he said."On the economic front, nothing concrete has been done to bring back the promised billions allegedly held abroad as black money. A hastily implemented demonetisation and GST have proved to be disastrous for economy."Petrol and diesel prices are at historic high despite the fall in international crude oil prices because the Modi government chose to levying excessive excise duty instead of passing on the benefit of the low prices to the people of India," he said.Singh termed the Modi government as having achieved "nothing more than a series of empty gestures" and characterized it with "foolhardy initiatives".