Senior Congress leader Digvijaya Singh on Wednesday night left Kerala for Delhi and is likely to file his nomination for the election to the party president's post on Thursday, sources said.
AICC general secretary (organisation) K C Venugopal was also in the same flight from Kerala to Delhi.
Singh and Venugopal were participating in the party's Bharat Jodo Yatra which was currently in Kerala.
Singh will hold a meeting of his supporters at night and is likely to file his nomination papers on Thursday, the sources added.
Nominations for the Congress president's election can be filed till September 30.
The former Madhya Pradesh chief minister is the latest entrant in the fray for the party chief's election, even as the fate of Rajasthan Chief Minister Ashok Gehlot contesting the party chief's election is uncertain.
(Inputs from PTI)