Celebrations broke out outside the Congress' office as party President Sonia Gandhi turned 71 on Saturday.
Scores of Congress workers waved balloons, burst crackers even as a cultural troupe performed a traditional dance outside Sonia's 10, Janpath residence, adjacent to the party headquarters.
Congress vice-president Rahul Gandhi, who is set to succeed his mother next week, took a break from hectic campaigning in Gujarat to be with her.
Rahul flew in from Vadodara late on Friday night and left for Ahmedabad on Saturday morning to hit the campaign trail in Gujarat.
He is addressing four rallies on Saturday.
Prime Minister Narendra Modi also extended birthday wishes to the Congress president. "Birthday greetings to Congress President... I pray for her long life and good health," Modi tweeted.
Parliamentary Affairs Minister Ananth Kumar also wished Sonia.
Sonia is set to relinquish her post next week, after 19 years at the helm of affairs of the Congress.