Prasad, the Minister of Electronics and Information Technology and also a Supreme Court lawyer, is contesting from the Patna Sahib constituency which has been a Bharatiya Janata Party (BJP) stronghold since over two decades.
Sinha quit the BJP and joined the Congress on April 6.
Both Prasad and Sinha belong to the upper Kayasth caste, who are present in sizeable numbers in Patna Sahib.
Sinha, who is fondly known as 'Bihari Babu', also visited different localities and villages in the constituency despite the scorching heat. Even his wife, Poonam Sinha has campaigned for him in Patna.
Ram Kripal Yadav, the Minister of State for Rural Development, is contesting from the Pataliputra seat which is a big challenge for him as jailed Rashtriya Janata Dal (RJD) chief Lalu Prasad's elder daughter Misa Bharti is also in the fray.
Misa Bharti, a Rajya Sabha MP, had contested unsuccessfully in the 2014 polls from the seat. She was defeated by Ram Kripal Yadav, who had quit the RJD and joined the BJP after being denied a ticket by Lalu Prasad in favour of his daughter.
Choubey, who is known to be a vocal supporter of Prime Minister Narendra Modi and also a champion of Hindutva politics, is trying hard to seek votes to retain the seat. But except his own Brahmin castemen, other upper castes, especially the Rajputs, are not in his favour.
R.K. Singh, a former IAS officer-turned-politician, is in the fray from the Arrah constituency, considered a Communist Party of India-Marxist-Leninist (CPI-ML) stronghold.
A Rajput, the BJP candidate is in a direct fight with CPI-ML candidate Raju Yadav, supported by the RJD and the Grand Alliance in the state.
With Raju in the fray, Singh has taken help from some tainted and criminal-turned-politicians belonging to the powerful Bhumihar upper caste, to woo voters. But the main problem is that ally Janata Dal-United leader Meena Singh has distanced herself from him.
Elections will be held for the Nalanda, Patna Sahib, Pataliputra, Arrah, Buxar, Sasaram, Karakat, Jahanabad constituencies in the last phase on May 19.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)