JOIN USCongress general secretary Digvijay Singh said Mayawati had set new records in corruption.
He alleged that Mayawati had "institutionalised corruption" and was ignoring the rights of the poor.
"For vested interests, the state government is allotting land to some industrialists only. On the other hand, she is not making any provision for the rehabilitation of the poor," he said.
Union Minister for Minority Affairs Salman Khursheed, referring to the life imprisonment awarded to two Bahujan Samaj Party (BSP) leaders in separate murder cases, said life imprisonment should be awarded to the BSP government "that would be dethroned in the upcoming assembly elections".
The convention was inaugurated by Congress MP Rahul Gandhi.
"I am here to listen to you all. So, I would first have your feedback and thereafter in the evening, I will give my views," he said after inaugurating the meet.
The Congress central leadership, including party president Sonia Gandhi and general secretary Rahul Gandhi, will set the party's agenda for the 2012 Uttar Pradesh assembly elections during this convention.
Sonia Gandhi will address the valedictory session Thursday, and will also hold a public rally at the Beniyabagh ground.
Asked why Varanasi was chosen as the venue, party officials said the historic importance of the city would help the party in connecting with the masses and strengthen its base in eastern Uttar Pradesh.
Congress frontal organisations - Seva Dal, Mahila Congress and Youth Congress - will also attend the convention.