Singh, a former BJP stalwart, said he and his associates had left BJP four years ago with a resolve to create a third front but it has failed.
He also refused to elaborate, saying there might be some reasons for the failure which he would not like to tell.
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Singh termed as uncalled for the dissent in the party against the merger with BJP, saying the decision had been taken through democratic process with a vast majority (two-third) of the party leaders supporting it.
"It is home coming," said the 68-year-old leader.
"Somehow, there had been a feeling in the HLP ranks that they should join hands with a national party and initially some people talked of Aam Admi Party (AAP) but majority wanted to go back to BJP and finally, I was authorised to take the call," he said.
Singh, who presently represents Kullu, said the entire HLP, barring a couple of persons who had their own 'prejudices', had put a stamp on the merger with the BJP.
He said he had already informed the Election Commission about the development and told the EC that HLPwasstill headed by him and if anybody else was representing to the EC on behalf of HLP, it should not be entertained.
Singh refuted the allegation that he had indulged in politics of opportunism, saying "Had I been an opportunist, I would have gone back to BJP ahead of Parliament polls in 2014.
"I had a big offer from BJP in the Parliament polls and it was very easy for me to have gone back. But I did not want that as I had formed HLP with a purpose and I had to decide within the party and go with the majority opinion," he said.
Singh said he had left BJP along with his supporters in February, 2012 to form HLP, over some issues.
Meanwhile, BJP has convened a 'Workers Maha sammelan' at Kullu on August 14, to be presided over by state party Chief Satpal Singh Satti and several senior party leaders.
The merger of HLP with BJP is expected to be announced at the 'Maha Sammelan'.