Samaj Party (BSP) supremo Mayawati to team up to defeat the BJP in Uttar Pradesh, where the BJP won 71 of the 80 Lok Sabha seats.

"I appeal to both Mayawati and Mulayam Singh Yadav to come together like we have come together to defeat the BJP," Lalu told the rally.

The BSP was wiped out in the Lok Sabha battle while the Samajwadi Party won just five seats.

Lalu Prasad said he and Nitish Kumar wanted to send a strong message across the country to unite non-BJP forces.

"It is a new beginning ... to ensure the formation of a strong alliance of like-minded people against the BJP," he said.

Lalu Prasad accused Prime Minister Narendra Modi of betraying the people by not fulfulling the election promise. "We have joined hands inview of the dangerous designs of the BJP," he said.

Nitish Kumar, who quit as Bihar's chief minister in May after his party was routed in the general election, also targeted Modi, saying that people were still waiting for the promised "achche din" (good days).

The JD-U won only two of the state's 40 Lok Sabha seats -- as against 20 seats in 2009 when it had allied with the Bharatiya Janata Party.

It parted ways with the BJP last year, ending a 17-year alliance.

Hundreds of RJD and JD-U supporters gathered at an open ground near Hajipur, about 30 km from Patna, since morning to witness the coming together of the leaders who have both served as Bihar chief minister.

State RJD president Ram Chandra Purve said both leaders will campaign together