Defying the party's stance, Sinha said, "Enough of negative politics and mudslinging by opponents on our political leaders, be it Kejriwal, Lalu Yadav or Sushil Modi."
"High time time to substantiate your claims..or pack up! Can't just keep feeding media with one night stories & sensationalising. Enough is enough," Sinha tweeted.
Backing the Delhi chief minister, Sinha said, "Individually I hold all political leaders, especially Kejriwal, in high esteem for their credibility, struggle and commitment towards society."
The BJP MP's remarks came at a crucial time when the party has been accusing both the leaders -Lalu and Kejriwal- of being involved in corruption cases.
Sinha's assertions drew sharp criticism from senior party leader Sushil Kumar Modi.
Modi said that it was not necessary to believe the actor and the party must remove such "traitors".
"It is not necessary to believe the man who is famous. The traitors must be sent out immediately," Modi tweeted.
"When Nitish (Kumar) didn't come out in support of Lalu (Prasad), in his support the enemies of BJP has jumped now," Modi said.
Reacting to Modi's tweet Sinha said positive and constructive criticism should not be taken as rebellion. Instead, it should ignite a debate within the party.
"Wouldn't like to comment on utterances out of frustration and desperation made against me by some vested interests and spoilers of inner party democracy. Some people who are wholly and solely responsible for our party's debacle in Bihar are today crying hoarse, hoping to regain their lost image," Sinha tweeted.
"Sycophants criticise for the sake of criticism and get low and personal. I pray that God should spare them for they know not what they speak," he said.
Calling Narendra Modi as "dashing dynamic action hero Prime Minister", Sinha said he wish party will take notice of "such unparliamentary utterances" of party leaders that "too against a senior party colleague and a staunch party loyalist".