“I am running for president,” Sanders said Wednesday. “I intend to stand up and fight for working families all over the country.”
Sanders, who is the longest-serving independent in congressional history, said he will run for president as a Democrat.
Sanders will hold a formal kick-off event in May, most likely in his home state of Vermont.
Sanders is a self-described independent socialist and will enter the race as a long shot.
Sanders, 73, currently serves as the ranking member of the Senate Budget Committee and previously served as the chairman of the Senate Committee on Veterans' Affairs.
Sanders first announced his presidential run in an interview with The Associated Press.
Watch "Good Morning America” for more from ABC News Chief White House Correspondent Jonathan Karl’s interview with Sen. Bernie Sanders.