The five-term representative released a statement saying: "As a former state legislator and a citizen, I care deeply about the issues that North Carolina faces as a state."
Miller announced last month he was not running for re-election.
He added, "I have been an energetic and determined candidate in the past. Although my determination to hold elective office appears now to be in remission, I may seek elective office again. And I will certainly support other energetic and determined candidates for office."
Miller has served in North Carolina's 13th District since 2003.
So far, Lt. Governor Walter Dalton, State Rep. Bill Faison, and former Rep. Bob Etheridge are in the race for governor on the Democratic side.