The SP won 37 of the 80 Lok Sabha seats in Uttar Pradesh in June last year but its performance dipped when it could bag only two of the nine assembly seats in the November bypolls.
Mehta defeated nearest rival Balwinder Singh Binder, an independent candidate, by 829 votes; Binder is known as a close aide of the AAP MLA Jagroop Singh Gill
Akhilesh Yadav claims violence in Sambhal was a conspiracy to distract from bypolls, demanding police accountability for the clashes that left four dead.