"Those (civil society leaders) who sit in their homes and hurl abuses on political parties and their leaders should learn from Kejriwal to form a political party (first) and (then) make whatever laws they want to," he told reporters after Congress party's coordination committee meeting here.
Singh's comments come close on the heels of his praising Kejriwal when he said that BJP's Prime Ministerial candidate Narendra Modi should learn austerity and humility from the AAP leader.
Singh said people critical about laws should realise the importance of forming a political party and contesting elections as Kejriwal did.
"People who wanted to make laws by hitting the roads at last have come to realise the necessity for entering the State Secretariat to enact laws. Therefore I had welcomed them when they formed a party," he added.
On projection of Kejriwal as Prime Ministerial candidate, Singh said "the media has already made Modi the Prime Minister and earlier L K Advani, and now the Delhi Chief Minister."
On Samajwadi Party government's move in Uttar Pradesh to withdraw cases against the accused in the Muzaffarnagar riots, Singh said it has the right to do so, but the step should stand the scrutiny in the court of law.
"Any state government has a right to withdraw charges against the accused, provided they are convinced the person is innocent, but even withdrawal of these cases has to be ultimately scrutinised and approved by the judiciary," he added.
The SP had yesterday backed withdrawal of cases against the accused in Muzaffarnagar riots, saying it was "trying to give justice to the victims".
On senior AAP leader Prashant Bhushan pitching for a referendum in Kashmir to decide whether or not the Indian Army should be deployed to deal with internal threats in the valley, Singh said the matter was best left to the Foreign Affairs and Defence Ministers to handle, and not answered by him here.