SP supremo Mulayam Singh's grand nephew Tej Pratap was leading over his nearest rival BJP's Prem Singh Shakya in Mainpuri Lok Sabha.
SP's Nawabjan won the Thakurdwara Assembly seat in Moradabad district by defeating BJP's Rajpal Singh by a margin of 27,023 votes.
In Lucknow, former BJP MP Lalji Tandon's son Ashutosh Tandon is leading.
The Assembly seats where bypolls were held include Saharanpur city, Bijnor, Thakurdwara, Noida, Nighasan Lucknow east, Hamirpur, Charkhari, Sirathu, Balha and Rohania, as also in Mainpuri Lok Sabha seat which was vacated by SP supremo Mulayam Singh Yadav.
Stakes are high for BJP, Congress, Samajwadi Party in Uttar Pradesh after the saffron party's near-total sweep of the 80 seats in Lok Sabha polls just four months.
