Former Punjab Chief Minister Captain Amarinder Singh, the chief of the Punjab Lok Congress (PLC) is expected to join BJP on September 19.
Singh will also merge his newly formed PLC party with the BJP.
He will join the BJP in the presence of party president JP Nadda and other senior leaders in Delhi.
Seven former MLAs and one former MP, who joined the PLC, will be among those to follow Singh on Monday.
The politician recently met with Prime Minister Narendra Modi and Union Home Minister Amit Shah amid rumours that he was likely to receive a major position in the BJP after joining it.
Capt Singh launched the PLC after leaving the Congress after being unexpectedly ousted as chief minister by the party's top leadership in September 2021.
Charanjit Singh Channi succeeded him as the Punjab chief minister up to the elections in February 2022.