The papers of all key candidates were found valid while those of eight independents--seven in Tamil Nadu and one in Karnataka-were rejected.
The stage is set for a contest in Uttar Pradesh and in Haryana while Union Power Minister Piyush Goyal and Chidambaram are among those who are set to be elected to the Upper House unopposed.
Several BJP MLAs, members of small parties and independents are backing Mahapatra.
Seven candidates of SP and two of BSP, including national general secretary Satish Chandra Mishra, senior Congress leader Kapil Sibal and BJP's Shiv Pratap Shukla are others who are in the fray.
In 403-member UP Assembly ruling SP has 229 MLAs, BSP 80, BJP 41, Congress 29, besides some smaller parties and Independents. Each candidate requires 37 votes for a win.
By contrast, in Tamil Nadu, nomination papers of seven independents paving the way for election of six nominees, four from ruling AIADMK and two belonging to DMK, unopposed to the Rajya Sabha.
Nomination papers of R Vaithilingam, A Navaneethakrishnan, A Vijayakumar, former Union Minister SR Balasubramoniyan (all AIADMK), and those of RS Bharathi and TKS Elangovan (DMK) were valid.
There will be no change in the number of DMK MPs which will continue to be four.
From Tamil Nadu, Congress Party will have no representation in the Upper House.
In Maharashtra, papers of all the six candidates, including Chidambaram and Piyush Goyal were found valid, and they are set to be elected unopposed as there are as many vacancies from the state. The others are Praful Patel (NCP), BJP's Vinay Sahasrabuddhe and Vikas Mahatme and Shiv Sena's Sanjay Raut.
Congress' decision to field third candidate, Ramamurthy, has given anxious moments to JD-S which needs five additional votes to see its candidate through, as it has 40 members.
