Kapil Sibal in an interview to news agency PTI slammed Jitin Prasada for crossing over to the BJP and said it represented politics of personal gains.
Sibal said he may think of leaving the Congress if his party thinks of him as "dead wood" or of no utility but would never join the BJP.
He further asserted that such a switch could only happen "over his dead body".
Sibal is a prominent member of the Congress' group of 23 leaders who wrote to party chief Sonia Gandhi seeking organisational overhaul last year.