In a brief address to media, Rahul, said, "there is a lot for us to think about. I hold myself responsible for the party's defeat."
His mother, Sonia, who won by a margin of over 3 lakh votes in Rae Bareli, said, "Mandate is clearly against us. As a party president, I accept people's mandate with humility."
While congratulating the new government, Sonia said, "Hope there will be no compromise on national interest."
She also thanked all party workers. Congress faced the worst ever defeat in its history.
Earlier in the day, Congress senior leader Kamal Nath said that they had not expected the kind of results that 2014 Lok Sabha polls had thrown up.
He also said that the "party needed to sit together and introspect as to where they had gone wrong."