Gandhi, who faced a volley of questions from the media on Singh's remarks on surgical strikes and the Pulwama terror attack, said he and the party completely disagreed with his statement.
Kharge is one of the most experienced persons in the party and is a Dalit leader too, said Manish Tewari, who is one of the proposers for Kharge's candidature.
The Thiruvananthapuram MP submitted his papers to the party's central election authority chairman Madhusudan Mistry at his office at the AICC headquarters.
Both candidates to file nomination papers tomorrow | Polling to take place on October 17, result on 19.
AICC general secretary (organisation) K C Venugopal was also in the same flight from Kerala to Delhi.
The 'bhoomi pujan' of the Ram temple is scheduled to be held on Wednesday at Ayodhya in Uttar Pradesh and Modi is expected to attend the event.
Nominations had been filed for 55 Rajya Sabha seats in 17 states for the March 26 election.
As the nearly day-long hearing witnessed forceful arguments by top advocates representing various sides, the court asked the Speaker when will a decision be taken on the resignations of the 16 rebels.
Ahead of apex court hearing on the Madhya Pradesh political crisis, he reached Bengaluru early morning on Wednesday and tried to go to Ramada Hotel where the rebel Congress MLAs are lodged.
Friday was the last date of filing of nominations for the biennial polls.