| Name of the Candidate | Party Name | Results |
| RATNESH SADA | Janata Dal (United) | Won 88789 |
| SARITA DEVI | Lok Jan Shakti Party | 35026 |
| MANOJ PASWAN | Jan Adhikar Party (Loktantrik) | 5443 |
| RAJKUMAR CHAUDHARY | Communist Party of India | 4830 |
| PRITHVI CHAND SADA | Independent | 2246 |
| CHANDAN RISHIDEO | Maanavvaadi Janta Party | 2238 |
| SATYANARAYAN PASWAN | Bahujan Mukti Party | 2007 |
| RAJESH RAM | Bahujan Samaj Party | 1809 |
| None of the Above | None of the Above | 6449 |
| AC No | Category | Poll Phases | Last Date of Nominations | Date of Polls | Result |
| 122 | SC | Phase V | Oct 18th 2015 | Nov 5th 2015 | Nov 8th 2015 |
Sonbarsha assembly segment, a part of the Madhepura Lok Sabha constituency, It is reserved only for the candidates coming from the Scheduled Castes (SC). Sonbarsha assembly constituency comprises Banma Itahari, Patarghat and Sonbarsha community development blocks. It is home to 2,57,470 eligible voters of whom there are a total of 1,33,779 male and 1,23,686 female voters.
One of the four assembly constituencies located in the Saharsa district of Bihar, Sonbarsa had elected Ratnesh Sada of the Janata Dal (united) in the last general assembly elections in Bihar in 2010. In that election, Ratnesh Sada came out with flying colours by polling 57980 votes to defeat his nearest rival Sarita Devi (Paswan) of the Ram Vilas Paswan led Lok Janashakti Party (LJP) by a huge margin of 31445 voters. Tarni Rishideo of the Congress came third with 10433 votes and was followed by DEO Narayan Paswan of the Communist Party of India (CPI) who received 4633 votes.
Other three assembly constituencies located in the Saharsa district are Simri Bakhtiarpur, Saharsa and Mahishi which were won by the JD (U), BJP and Rashtriya janata Dal (RJD) respectively in 2010.
Earlier Kishore Kumar had emerged victorious from the Sonbarsa assembly constituency in both the elections in 2005 as an independent. While Kishore Kumar had defeated Ranjit Yadav of RJD in October /November 2005, in February 2005 polls he had trounced the sitting RJD MLA Ashok Kumar Singh who had defeated Kishore Kumar in 2000. Ashok Kumar Singh had also claimed the seat in 1977, 1990 and 1995.
Sonbarsa is one of the six assembly constituencies that combine to form the parliamentary constituency of Madhepura which is currently represented by Rajesh Ranjan, popularly known as Pappu Yadav of the RJD who won the seat by defeating the sitting JD (U) MP Sharad Yadav by a margin of 56,209 votes in the 2014 Lok Sabha elections. Vijay Singh Kushwaha, who contested on the ticket of the BJP, came third. Bihariganj Vijay Singh Kushwaha is the husband of sitting Bihariganj JD (U) MLA Renu Kushwaha.
Other five assembly constituencies that fall under the Madhepura Lok Sabha seat are Madhepura, Bihariganj, Alamnagar, Saharsa and Mahishi.
Lok Janshakti Party (LJP) has fielded Sarita Paswan from Sonbarsha, a constituency reserved for the scheduled castes. She will take on the sitting MLA Ratnesh Sada from JD(U). Both have faced each other in 2010 assembly election. Hence, they are old rivals and are well-aware of each other's campaign strategy. People are divided on caste lines. But the youth are rising above caste limitations as they now aspire to achieve more.
The young voters are looking into factors like development including better roads, social infrastructure and job opportunities near the neighbourhood so that they don't need to migrate to cities. Sonbarsha, at present, is represented by Ratnesh Sada of JD(U). Sada grabbed the seat by winning 56,633 votes in the 2010 assembly election. Sarita Devi of LJP had to content with 25,188 votes. Sonbarsha is in Saharsa district.