In a move that will further irk his party, BJP parliamentarian Shatrughan Sinha on Friday congratulated Bihar CM Nitish Kumar and called Congress vice-president Rahul Gandhi a "rising star."

Just hours before the oath-taking ceremony of the new Bihar cabinet members, the Rajya Sabha MP remarked that the victory of the Mahagathbandhan (Grand Alliance) was the victory of democracy.

"It has been the victory of democracy. I wish the new government led by Nitish babu, Laluji and rising star Rahul Gandhi great success," read the tweet posted on Thursday night.

On Wednesday, he had challenged the party leadership to act against him after the BJP Bihar unit urged senior leaders to rein in the lawmaker for his anti-party statements.

"RK Singh, former Home Secy & a proud Bihari Sher (a tough nut to crack) is right. No one has the guts (or DNA) to give us a 'fatkar'," he had tweeted on Wednesday.

Last week, the BJP veterans including LK Advani defended the disgruntled parliamentarian, after he criticised the party top brass for the Bihar debacle.