"The BJP has mastered the politics of 31 per cent votes where the rest do not matter. However, in a vibrant India, every citizen must remain an equal stakeholder. I aspire to make this happen," Kumar said on a social networking site.
"India stands at a critical juncture in its progress as a democracy. The nation needs a strong opposition that can voice the idea and aspiration of India, which BJP cannot appreciate and represent," Kumar added.
The merger is being touted as the precursor to the unification of six parties who came into existence after breaking away from Janata Dal formed by former prime minister V P Singh in 1988.
The six parties are JD(U), Rashtriya Janata Dal, Samajwadi Party, Indian National Lok Dal, Janata Dal (Secular) and Samajwadi Janata Party (SJP).