Former prime minister and senior Congress leader Manmohan Singh on Tuesday filed his nomination papers for the by-poll to the Rajya Sabha from Rajasthan.
Chief Minister Ashok Gehlot and his deputy Sachin Pilot accompanied the former prime minister.
The seat fell vacant following the death of state BJP president Madan Lal Saini, who was elected to the Rajya Sabha last year when the BJP was in power in the state. Now, the Congress is ruling Rajasthan.
The former prime minister had represented Assam in the Rajya Sabha for 28 years before his tenure ended earlier this year.