Singh, who had met BJP chief Amit Shah in Delhi two days ago fuelling speculations that he may may dump Congress on Thursday said that he would attend a rally at Kaithal on August 18, to which Shah too has been invited.
Singh is a known detractor of the state Chief Minister Bhupinder Singh Hooda.
Earlier in the day, Singh met his supporters at his home turf Uchana in Jind district to seek their feedback to decide on his next step.
"I wanted to seek their feedback, I am on the crossroads (of my political career). A vast majority of them said that I should quit Congress and join the BJP," he said.
Birender Singh does not like to mix relation with politics.
Singh's supporters also told him that he had not got his due in Congress and that they would back him if he joins BJP.
In his hard-hitting speech at Uchana, Singh, who has been associated with the Congress for over four decades, hit out at his bete noire Hooda and even did not spare former Chief Ministers including Bansi Lal and Bhajan Lal, saying all of them had failed to carry out equitable development in Haryana and had remained confined to their pocket-boroughs.
Singh said he has full regards for Congress chief Sonia Gandhi and Vice President Rahul Gandhi, but slammed Hooda accusing him of practising regional bias in carrying out development and claimed his continuance is damaging the party.
Singh also made public his displeasure over his non-inclusion in the Union Cabinet in the erstwhile UPA government. He said he was all set to be sworn in as a Cabinet Minister in the UPA's Ministry last year, but at the last moment he had been told that he cannot be given the berth because of some reasons.
Singh, a former Haryana minister, lost the 2009 Assembly polls to former Chief Minister Om Prakash Chautala from Uchana Kalan segment.
Earlier, Birender Singh had charged Hooda with weakening the Congress. "I don't know how the party will overcome and deal with the damage that has been caused. After the Lok Sabha poll debacle, I had said that Hooda should step down on moral grounds and demanded that he should be changed. Though it is quite late, Hooda should forthwith leave the Chief Minister's post because there is growing resentment and disillusionment among Congress rank and file," he said.
Despite being a cousin of Hooda, Birender does not like to mix relation with politics.
Referring to his relation with BJP's national spokesman Capt Abhimanyu, Birender said "like Abhimanyu is my relative, Hooda is also my brother in relation. But you see these relations have their own place in the social setup, but these cannot be mixed with politics. I have my own principles in politics and I never compromise on these".
The Haryana Congress unit has been facing an exodus of leaders, some of whom have joined the BJP camp, since the last Lok Sabha polls.
Prominent Congress leaders who have switched over to the saffron party include Rao Inderjit Singh, who had also been vocal against Hooda.
Rao, who was then a Congress MP from Gurgaon, severed his four-decade old ties with Congress and contested as BJP nominee from Gurgaon and retained his seat. He is now a minister in the Narendra Modi government.
Senior leader from Bhiwani region Dharambir also switched over to BJP and is now an MP from Bhiwani-Mahendergarh seat.
Former Union minister Venod Sharma too severed his four-decade old ties with the Congress to float his own Jan Chetna Party. Another turncoat, Ramesh Kaushik, won the Sonepat Lok Sabha constituency on a BJP ticket after quitting the Congress.
(With PTI inputs)