Samajwadi Party MP Surendra Nagar resigned from Rajya Sabha on Friday and is likely to join the BJP, official sources said.
The resignation of Nagar, an influential Gurjar leader from western Uttar Pradesh, has been accepted by Rajya Sabha Chairman M Venkaiah Naidu, they said.
The sources said Nagar met senior BJP leaders in Parliament after his resignation.
He is likely to join the saffron party and may be re-elected to the Upper House on its ticket, they said.
A number of Rajya Sabha members from opposition parties have joined the BJP of late.
Sanjay Sinh of the Congress and Neeraj Shekhar of the Samajwadi Party also joined the saffron party after quitting their parties and Rajya Sabha membership.
Four TDP members had also joined the BJP earlier.