"Sonia Gandhi's rally will resuscitate the Congress. There will be a huge crowd in the rally," Delhi Congress chief spokesperson Mukesh Sharma said.
According to experts, retaining Delhi's seven parliamentary constituencies would be an uphill task for the Congress whose image has been marred by a string of corruption scandals.
Gandhi - also the chairperson of the ruling United Progressive Alliance - will address a public rally at Ajmal Khan Park in New Delhi constituency represented by Ajay Maken. The contest in New Delhi will be triangular with the entry of AAP.
Maken will face BJP's Meenakshi Lekhi and Aam Aadmi Party's journalist-turned-politician Ashish Khetan.
Sources told IANS the party workers are making every effort to make the rally successful. "All our preparations are done for tomorrow's (Sunday) rally," said a Congress leader.