Maintaining that election of Rajnath Singh as BJP President is an internal matter of the party, Union Minister and Congress leader Rajiv Shukla went on to take potshots at the saffron outfit, seeking to know the "mystery" behind "overnight coup" involving the appointment.

"It is their internal matter. BJP always has an issue on who will become their chief and still it claims to be a democratic party. This overnight coup, I don't think I will get to see in any other party, where one chief is suddenly replaced by someone else. What is surprising is that they claim they elect their leader democratically," he said today.

Singh was today unanimously elected President of BJP, capping last minute dramatic turn of events which saw Nitin Gadkari being forced out of the race for the second term.

"They should have given the reason why Gadkari resigned.

What happened overnight that he had to resign? The entire day, their spokesman was praising Gadkari.

"Suddenly, what happened at night that all the praises changed into criticism and they accepted his resignation and brought in a new person. I think this mystery should be uncovered," he added.