Singh today expelled two MPs Devender Nagpal and Sarika Baghel from the party for hobnobbing with the Samajwadi Party.
RLD has also sought their disqualification in a petition to the Lok Sabha Speaker Meira Kumar.
Baghel is a Lok Sabha member from Hathras while Nagpal represents Amroha, both in western Uttar Pradesh, the home turf of RLD chief and Civil Aviation Minister Ajit Singh.
Disciplinary action against the two MPs was on the cards in the wake of reports that Baghel had been declared SP candidate from the Agra Lok Sabha constituency while Nagpal had joined the SP and was in the queue for the ticket.
Uttar Pradesh is witnessing a trend of party hopping among MPs who have been denied ticket for Lok Sabha elections by their parent parties.
RLD has five members in the Lok Sabha including Ajit Singh elected from Baghpat and his son Jayant Chaudhary from Mathura.