Manmohan Singh arrived at Sonia Gandhi's residence to greet her.
Senior party leaders who arrived at Gandhi's residence included Moti Lal Vora, Digvijaya Singh, Mallikarjun Kharge, P. Chidambaram, Janardan Dwivedi, Kamalnath, Ambika Soni, A. K. Antony, Mukul Wasnik.
Earlier in Morning Congress leader Jyotiraditya Scindia also took to twitter and wrote: "Warm birthday greetings to Sonia Gandhiji on her 70th birthday. May God bless her with the best of health and happiness always."
Sonia Gandhi is the longest serving President of the Congress since 1998. She was married to former Prime Minister Rajiv Gandhi, who was assassinated in 1991.