The letter is an indirect attack on BJP leader Jyotiraditya Scindia, who took oath as Rajya Sabha MP on Wednesday, and is likely to be inducted in the Union Cabinet after he led a successful revolt against Kamal Nath, which led to the fall of the Congress government in Madhya Pradesh.
Attacking the Central government, Kamal Nath said, "It's not a matter of the Congress government only, but the whole democratic setup has been shaken. There is a kind of earthquake in the democratic setup and I doubt that at the centre of this is the Centre (Union government). I hope my doubts are baseless."
He further alleged that there is always an attempt to destabilise the government through unfair means wherever the opposition is in power.
On Thursday, another Congress MLA resigned from the party, dashing the hopes of Congress of making a comeback in the state after the by-elections.
The Congress is facing a similar revolt in Rajasthan where 18 MLAs along with former Deputy Chief Minister Sachin Pilot have rebelled and the matter is pending at the Rajasthan High Court.