Rabri Devi was fielded by RJD in Saran from where Lalu Prasad won in 2009. But, he had to quit after being convicted in a case of the multi-crore fodder scam last year.
Sadhu deserted RJD five years ago and joined the Congress. Later, he also quit Congress and tried to join the BJP.
BJP has fielded Rajiv Pratap Rudy from Saran.
The Congress and the RJD early this month announced their alliance under which RJD was to contest 27 of the state's 40 Lok Sabha seats, the Congress 12 and the Nationalist Congress Party one.