"Polling for the fourth phase covering 11 districts started at 7am amidst tight security arrangements," Chief Electoral Officer Umesh Sinha said.
[Read More: Uttar Pradesh assembly election 2012].
This phase would decide the fate of three ministers, 32 sitting MLAs and 12 former ministers.
More than 1.74 crore voters are expected to cast their votes to seal the fate of 967 candidates in the polling to be held in Hardoi, Unnao, Lucknow, Rae Bareli, Farukkhabad, CSM Nagar, Kannauj, Banda, Chitrakoot, Fatehpur and Pratapgarh.
Stakes are high for ruling BSP, Congress, SP and the BJP in the no holds barred fight for the 403 assembly seats.
This phase has 103 candidates with criminal cases pending against them, besides 139 'crorepatis'.
The CEO said that polling was being held at 18608 polling booths at 12821 centres. Total 3393 polling booths have been identified as sensitive and 3623 as hyper-sensitive.
The fourth phase would test fate of several stalwarts and heavyweights, including three ministers, 32 sitting MLAs, 12 former ministers, national vice-president of BJP Kalraj Mishra and Congress state president Rita Bahuguna Joshi.
In this phase, senior BJP leader and Rajya Sabha MP Kalraj Mishra is making his debut in electoral politics from Lucknow east seat, whereas UPPCC president Rita Bahuguna Joshi is in fray from Lucknow Cant seat.
This phase would also test the luck of Louis Khurshid, wife of Union Law Minister Salman Khurshid from Farukkhabad Sadar seat.
Congress Legislative Party leader Pramod Tiwari is seeking a re-run from his traditional Rampur Khas seat in Pratapgarh district.
Among ministers while Urban Development Minister Nakul Dubey has shifted to Bakshi ka Talab seat, Science and Technology Minister Abdul Mannan is re-contesting from Sandila seat.
Chairman of Housing and Development Board Achche Lal Nishad is in fray from Tindwari and chairman of UP Agro Brijmohan Singh Kushwaha from Baberu seat.