Anjan Dutta, president of the Assam Pradesh Congress Committee (APCC), passed away on Thursday morning at AIIMS.
Dutta, 64, had been undergoing treatment at AIIMS for the past one month.
Congress vice president Rahul Gandhi had visited Dutta to inquire about his health.
Dutta was three times MLA from the Amguri Constituency.
He had also served as the president of the Assam Pradesh Youth Congress Committee and the chairman of the North East Youth Congress Co-ordination Committee.