Bihar Chief Minister Nitish Kumar on Wednesday said that he joined forces with RJD chief Lalu Prasad Yadav to ensure the defeat of the BJP-led NDA in the state assembly polls."It was necessary to tie up with RJD chief Lalu Prasad to defeat the BJP, in view of the prevailing situation," Nitish Kumar told mediapersons here, a couple of days ahead of the second round of the five-phase polls."I want to made it clear that good governance and development will be our main agenda and will continue if the grand alliance of JD-U, Rashtriya Janata Dal and Congress comes to power after polls," Nitish Kumar said.Earlier, Nitish Kumar downplayed corruption allegations levelled by BJP and its allies during campaigning.The Bharatiya Janata Party-led National Democratic Alliance is determined to oust the ruling Janata Dal-United and its allies.