He was the senior leader of Janta Dal ( United) .He was the Chief Minister of Bihar from 21st April 1979 to 17th February 1980. In 1991, he was elected to the 10th Lok Sabha from Hajipur constituency in Bihar. In 2009, he was re-elected to the 15th Lok Sabha from the same constituency. He contested from Hajipur again in 2014 general election at the age of 93 , but was defeated by Ram Vilas Paswan. Ram Sundar Das was one of India’s oldest candidates in that general election. This news was coverd by BBC .
On this occasion Chief Minister Nitish Kumar also inaugurated the base for the construction of Statue of Late CM Ram Sundar Das. Nitish also mentioned about this great leader . He gave the details how Late Ram Sundar Das contributed in Bihar development and politics.