"It is alright if Sushma feels that Modi is good for the prime minister's job, but she must first tell if Advani also agrees with her on this," Digvijay said, talking to reporters at Dokaria village in Madhya Pradesh's Katni district.
Swaraj had said on Saturday that the Gujarat chief minister is fit to become the prime minister.
On media speculation that P Chidambaram could be the next prime minister if Congress retained power, Digvijaya said his party always stuck to the tradition of MPs choosing the prime minister.
On land reforms bill, he said UPA wanted to bring it in Parliament but could not do so due to compulsions of coalition politics.
BJP-HJC alliance firm as a rock in Haryana: Swaraj
The politics behind the hanging of Kasab
Police personnel cast their votes in Gujarat
PHOTOS: Politicians, actors at Bal Thackeray's funeral
Modi fit to become prime minister: Sushma Swaraj