He took potshots at Nitish Kumar for his efforts to forge unity among the opposition ranks.
Former Janata Dal (United) president RCP Singh joined the BJP here today in the presence of Union minister Dharmendra Pradhan and accused Bihar Chief Minister Nitish Kumar, once his mentor, of compromising with crime and corruption in his pursuit of "kursi" (chair).
Once a close confidant of Nitish Kumar, RCP Singh had a fallout with him last year as he was seen by his party to be veering closer to the BJP as the differences between the two parties grew leading to the subsequent severance in their ties.
Joining the BJP, he took a swipe at his former mentor, saying Mr Kumar had compromised with his stand against crime and corruption in his love for the chair. He will be left with nothing in Bihar, Mr Singh said and lauded Prime Minister Narendra Modi for his work for the poor and overall leadership of the country.
In his strong remarks against the Bihar chief minister, he mocked him as "palti maar" (someone who keeps taking a U-turn) and said he was and will remain "PM (palti maar)".
Mr Singh said if no work is happening in the country, then how did India become the fifth largest economy in the world.
The former Cabinet minister, who had to resign from the Modi government after the JD(U) did not nominate him to Rajya Sabha for a fresh term last year, took potshots at Mr Kumar for his efforts to forge unity among the opposition ranks.
Mr Kumar was given the mandate of Bihar's development but he has been travelling from one state to another, he said.
Mr Pradhan lauded Mr Singh, claiming that he played a key role in strengthening the JD(U) in the state and enjoys credibility among the extremely backward sections of society.
A bureaucrat, Mr Singh served under Kumar when he was a Union minister and was brought into politics by the JD(U) leader. He was nominated to Rajya Sabha twice and was for long the most powerful leader in the party after Nitish Kumar before their fallout.
He also comes from the Kurmi caste like Mr Kumar.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)