Paswan, who had left NDA in 2002 over the 2002 Gujarat riots, came back to the BJP-led alliance on Thursday.
Under the seat sharing agreement between the two parties, LJP would contest seven of the 40 Lok Sabha seats in Bihar. The new tie up came as a jolt to Congress' plans to have a "secular" alliance with his party and RJD.
Of the remaining 33 seats in Bihar, BJP intends to contest 30 with three being given to Upendra Kushwaha's Rashtriya Lok Samta Party (RLSP).
Under the deal, LJP will contest from Hajipur, Samastipur, Jamui, Munger, Vaishali, Nalanda and Khagriya.
BJP President Rajnath Singh had said that Paswan will meet Advani and BJP's Prime Ministerial candidate Narendra Modi in the next few days. The LJP supremo will also share the dais with Modi at the latter's rally on March 3 in Muzaffarpur in Bihar.