Janata Dal-United president Sharad Yadav said on Friday that the alliance with Lalu Prasad's Rashtriya Janata Dal for legislative assembly elections scheduled later this year was "sure and certain"."The alliance between the JD-U and RJD is sure and certain. But I cannot give a date for it," Sharad Yadav told media after holding a closed door meeting for three hours with Bihar Chief Minister Nitish Kumar here.The JD-U president downplayed the differences between the two political parties over the projection of a chief ministerial candidate. "The alliance will be finalised soon and talks will continue on other issues," he said before leaving for Delhi.Yadav said he was confident of a strong (pre-poll) alliance of JD-U, RJD and the Congress."A strong secular alliance is need of the time to ensure the defeat of BJP in Bihar's polls," he said.