"Good RJD leaders must join JD(U) which is upholding secularism and working for the uplift of poor and downtrodden," Singh told PTI.
"RJD is no more a party... Is there anything left in that party for someone to lead," he asked.
The senior minister, however, refused to comment on the CBI court judgement on the RJD chief and 44 others in one of the multi-crore fodder scam related case.
"After Prasad's going to jail whatsoever is left (of RJD) will also finish," the minister added.