Both ministers are likely to be elected unopposed to the upper house of parliament with the Bharatiya Janata Party (BJP) having a clear majority in the 90-member Haryana assembly and no other nominations likely to be filed by other parties.
Prabhu and Birender Singh reached the Haryana assembly complex, accompanied by Haryana Chief Minister Manohar Lal Khattar, ministers in the Haryana government and senior BJP leaders.
Prabhu was recently inducted into the Narendra Modi government at the centre and had joined the BJP just before becoming a minister. He belongs to Maharashtra and was earlier with the Shiv Sena.
Birender Singh, who left the Congress in August this year after being with the party for 42 years and joined the BJP before Haryana's assembly polls, was also inducted as a union cabinet minister.
Singh had quit his Rajya Sabha seat from Haryana in August this year. Under the rules, both had to get elected to parliament within six months of becoming ministers.
With the two new union ministers likely to be elected from Haryana to the Rajya Sabha, the representation of the state in the Modi government will go up further.
Haryana already has three union ministers, External Affairs Minister Sushma Swaraj (who belongs to Haryana), Minister of State for Defence Rao Inderjit Singh (Gurgaon MP) and Minister of State Krishan Pal (Faridabad MP).