Samajwadi Party candidate Dimple Yadav was leading with 4,800 votes after the third round of counting from Mainpuri Lok Sabha seat.
She has established a lead over her nearest rival Raghuraj Shakya of the BJP.
BJP spokesman Harish Chandra Srivastava said that it was too early to make any statement and the BJP was confident of wresting the seat from the SP.
The seat fell vacant after the demise of party patriarch Mulayam Singh Yadav.
