Kapil Sibal's resignation is the latest high-profile exit from the Congress.
Former Union Minister Kapil Sibal revealed today that he has quit the Congress party, dropping a bombshell moments after filing his nomination papers for Rajya Sabha as an independent candidate supported by the Samajwadi Party.
"I had resigned from the Congress party on May 16," Kapil Sibal told reporters, slipping in information that had stayed concealed since the Congress "Chintan Shivir" or strategy meet a week ago.
"I am no longer a senior Congress leader," he quipped, when bombarded with questions.
Mr Sibal resigned a day after the Congress brainstorming session held to discuss a roadmap for the party's revival after a series of devastating election defeats. He had been left out of the big meet and was no longer a part of the Congress' advisory groups.
"I had a deep relationship with the Congress. It was for 30-31 years. This is not a small thing. I joined the Congress because of Rajivji (former prime minister Rajiv Gandhi). You must be thinking, how can one leave the Congress after 31 years. There must be something that my heart must feel. Sometimes, such decisions need to be taken. But my ideology is that of the Congress. I am not far away from the Congress and its ideology. I am with the sentiments of the party," he said.
"We are all constrained by the fact that we are members of parties and have to abide by the discipline of that party, but it is important to have an independent voice. When the voice of an independent is raised, people will feel that he is not associated with any other party."
This is the latest high-profile exit from the Congress and the fifth in five months.
Like most exits it has seen in the past two years, this one is also not a surprise for India's oldest party.
Mr Sibal, an ace lawyer who has represented politicians across the spectrum and once among the senior most leaders of the Congress, was the driving force behind the "G-23" or group of 23 dissenters who had called for a complete overhaul of the party's leadership and organization in a letter to party president Sonia Gandhi two years ago.
He has been vocal and increasingly sharp in his criticism of the Gandhis' leadership, especially Rahul Gandhi. He had also openly called for a non-Gandhi as Congress chief.
Mr Sibal's Rajya Sabha term ends in July. In 2016, he was elected to the Rajya Sabha from Uttar Pradesh as a Congress candidate supported by the Samajwadi Party, which is in power in the state. The Congress now has just two MLAs in the UP assembly so it cannot elect anybody to the Rajya Sabha from the state.
The Samajwadi Party has 111 MLAs in the 403-member UP assembly and can send three members to the upper house of parliament. The BJP has 255 members and can send eight members to Rajya Sabha.
Mr Sibal filed his nomination papers in the presence of Samajwadi Party chief Akhilesh Yadav.
The Samajwadi Party's move to support Mr Sibal is seen to a quid pro quo after his efforts as party MLA Azam Khan's lawyer.
Mr Sibal had represented Azam Khan in the Supreme Court. Azam Khan was released on interim bail by the Supreme Court after two years in prison.
The Rajya Sabha elections next month will include 11 Uttar Pradesh seats.
"Kapil Sibal is the first person we have chosen for the Rajya Sabha election. Two more nominations will be announced soon," Akhilesh Yadav said.