"The state unit of the party is not functioning as it should. It should be above caste politics," Singh said in a letter addressed to Congress President Sonia Gandhi.
Apparently referring to Union Minister Srikant Jena and OPCC President Jaydev Jena, Singh wrote, "Party cannot function at the whims of two or three individuals many of whom do not subscribe to party ideology."
Requesting Sonia Gandhi to accept his resignation, Singh claimed that many senior leaders felt ignored. "Even the coordination committee is ignored."
Asked who he blamed for the prevailing situation in Congress, Singh said "One of them is Srikant Jena." Singh revealed that he was told by the party's state leadership to resign from the post of Leader of Opposition after end of the last session of the Assembly.
"I was told that a dalit has been OPCC president and the leader of Opposition should be from tribal community. I asked them what is the point to make a tribal leader of Opposition when there is no session of Assembly," Singh said.
Meanwhile, BJD supremo and Chief Minister Naveen Patnaik welcomed Singh and Sai into his party.
"I am delighted that Singh, leader of opposition, Sai, MLA from Brajrajnagar and young leader from Kalahandi Ranjit Singh have joined BJD," Patnaik said
Singh alleged it was done to keep him away from the decision making in the candidate selection and other activities ahead of elections though AICC general secretary in-charge B K Hariprasad stated that the Congress would go to polls under the leadership of Jaydev Jena and him.
"Original Congress people are not being given party tickets. As I am opposed to it, they wanted me out of the screening committee of which I am a member as the Leader of the Opposition," Singh said, adding he was kept in dark in many cases like party's candidate selection for Rajya Sabha polls.
Accusing state leadership of ignoring views of district committees, he said "The state leadership keeps Sonia Gandhi and Rahul Gandhi in dark. They too held the Pradesh Election Committee meeting away in Delhi so that state leaders cannot get to know what is happening in the party." Asked if Congress had forgotten its ideology, Singh said "Party is not wrong, but some people at the helm do wrong things."
Asked how he could accept Naveen Patnaik as his leader after alleging he was corrupt and an autocrat some days ago in the Assembly, Singh said he was then performing his duty as a leader of Opposition in the House.
"Anyway, calling a man corrupt does not mean anything until allegations are proved," he said.
Stating that Patnaik was his leader, Singh said the BJD government has taken a lot of steps for the uplift of poverty stricken KBK (Kalahandi-Bolangir-Koraput) region to which he belonged.
Anup Sai said, "I have joined BJD in order to ensure development of my constituency. There is no democracy in the state Congress."
OPCC president Jaydev Jena said Singh's resignation would have no impact on the electoral prospects of the party.
Union Minister Srikant Jena spoke in a similar vein.
"Singh's resignation will not damage the party. Rather he will suffer damage."
Meanwhile, the AICC named MLA Surendra Singh Bhoi as the new leader of Opposition in the Odisha Assembly.