Bihar's longest serving chief minister Nitish Kumar and BJP president Nitin Nabin are set to enter Rajya Sabha unopposed while NCP-SP supremo and veteran politician Sharad Pawar will return to the upper house once again after they filed their nomination papers on Thursday. The leaders were among the 40 candidates who filed their papers on the last day of nomination for 37 seats that are falling vacant in 10 states, leading to a keen contest for one seat each Bihar, Odisha and Haryana. Seven seats are falling vacant in Maharashtra, six in Tamil Nadu, five each in Bihar and West Bengal, four in Odisha, three in Assam and two each in Haryana, Telangana and Chhattisgarh, besides one seat in Himachal Pradesh. The scrutiny of papers will take place on Friday, and the nominations can be withdrawn till March 9. If needed, polling will be held on March 16. In Tamil Nadu, West Bengal and Assam, assembly elections are likely to be held in April. The BJP is set to increase its tally in the Up