The reshuffle, which will take place on Sunday morning, is expected to see induction of new faces, including actor-turned-politician Chiranjeevi.
80-year-old Krishna, a former Chief Minister of Karnataka, sent his resignation to Prime Minister Manmohan Singh after apparently being told of plans to revamp the Cabinet. It has since been accepted.
Krishna, who was surprisingly made the External Affairs Minister after 2009 elections, said he was stepping down to pave the way for youngsters and strengthen the hands of leadership for strengthening the party.
There were indications that he could be asked to lead the Congress in Karnataka where assembly polls are due next year.
Late in the night, reports emerged that Information and Broadcasting Minister Ambika Soni and Social Justice Minister Mukul Wasnik also had offered to quit to work for the party.
Whether Rahul Gandhi would join the government is still a matter of conjecture even as the Prime Minister held consultations with Congress President Sonia Gandhi for about an hour, apparently to give final touches to the exercise.
Some more Ministers are likely to quit ahead of the reshuffle, which could be the last before the Lok Sabha elections slated for 2014.
Among the probables for induction are Chiranjeevi, whose 18 MLAs provide stability to the Congress government in Andhra Pradesh after the merger of his party PRP.
Speculation is that former Chief Minister K Vijay Bhaskar Reddy's son Surya Prakash and two MPs from Telengana region are likely to be made union ministers. (MORE)
