RJD supremo Lalu Prasad's elder son and Janshakti Janta Dal chief Tej Pratap Yadav finished a disappointing third in Mahua constituency.
The LJP(RV)'s Sanjay Singh won by a margin of 44,997 votes, receiving a total of 87,641 votes.
Incumbent RJD MLA Mukesh Kumar Raushan finished second in the Yadav-dominated constituency with 42,644 votes.
Tej Pratap came in third with a total of 35,703 votes.
He had recently floated a new political outfit, the Janshakti Janata Dal (JJD), after being expelled from the RJD by his father.
He was expelled on May 25 for six years, a day after he reportedly confessed to being 'in a relationship' with a woman.
He, however, deleted the social media post later claiming that his page was "hacked". Lalu Prasad also disowned Tej Pratap due to his "irresponsible behaviour".
Tej Pratap won the Hasanpur Assembly constituency in 2020 on an RJD ticket. In 2015, he won the Mahua Assembly seat.