Thakur is a sitting Rajya Sabha member, and also the BJP's national vice president.
Last week, the party re-nominated Thakur, and named R.K. Sinha -- who worked with former party chief Nitin Gadkari in the Delhi assembly polls -- as another candidate for the Rajya Sabha which has five seats from the state up for elections this time.
Thakur is a sitting Rajya Sabha member, and also the BJP's national vice prez.
Thakur belongs to the powerful land-owning upper caste of Bhumihars. The BJP leadership is confident of the support of his caste after its alliance with Chief Minister Nitish Kumar's Janata Dal-United (JD-U) ended last June.
Sinha is also not a new face in the saffron party in the state. His name cropped up a few years ago for the upper house of parliament, but he was not nominated because of caste equations in state politics being then unfavourable.
"He was aspiring to enter the Rajya Sabha for the last several years, and that aspiration has now been fulfilled," BJP leader Sanjay Mayunkh said.
Sinha, who belongs to the Kayastha caste, is no longer considered an influential person in state politics. He runs one of the biggest private security agencies in the country, SIS (Security and Intelligence Services India Ltd.), and has a long association with the saffron party.Earlier, the ruling JD-U had announced the nomination of three new faces for the Rajya Sabha elections from the state.