Senior Congress leader Ahmed Patel on Monday took oath as the Rajya Sabha MP.
Chairman M. Venkaiah Naidu administered the oath of secrecy to the Congress leader.
Finance Minister Arun Jaitley was also present at Patel's oath ceremony.
Congress leader Ahmed Patel retained his Rajya Sabha seat after polls in Gujarat on August 8, even though few legislators deserted the party days before the election and cross-voted.
Patel also said that the win had boosted the morale of the whole party.
After the victory, Patel had alleged that the election exposed the "personal vendetta and political terror" of the BJP.
Earlier on August 25, Bharatiya Janata Party (BJP) president Amit Shah and Union Minister Smriti Irani also took oath as Rajya Sabha MPs.
The BJP lacks majority in the House and it is being said that Shah's entry into the Rajya Sabha would give a boost to the party.
