Sources said the two leaders had separately called up Kejriwal and lauded his stunning victory in the elections in which the BJP faced a humiliating defeat.
After organisational changes in BJP, both Advani and Joshi are now part of the party's newly-formed 'margdarshak mandal', a group formed to guide the party after they were ousted from BJP's top decision-making bodies - the Parliamentary Board and the Central Election Committee.
Prime Minister Narendra Modi has already congratulated Kejriwal and the AAP leader also called on him on Thursday morning.

AAP not to send invites to political parties
Aam Aadmi Party will not send invites to the leaders of any political parties or chief ministers of any state to attend Arvind Kejriwal's oath taking ceremony on Saturday.
The party said it had invited only to Prime Minister Narendra Modi, Union Home Minister Rajnath Singh, Union Urban Development Minister Venkaiah Naidu and seven MPs representing Delhi in the Lok Sabha for the ceremony at Ramlila Maidan.
Party sources said unlike last time when Kejriwal had travelled in Delhi Metro to reach Ramlila Maidan for swearing- in ceremony, he will come in a car this time, accompanied by his family.
Meanwhile, around 50,000 to 1 lakh people are expected to attend the swearing-in ceremony at the Ramlila Maidan this time. The Delhi government will make the seating arrangement for 35,000 people.

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