Miller's office issued a statement Thursday morning saying he wants to avoid running against fellow Democrat David Price in a primary after the Republican-controlled Legislature drew them into the same district.
Miller says he does not have an agreement with Price to step down and run again in two years when Price is expected to retire.
Miller says he will continue to press hard for reform of the banking industry. He says he's also hopeful of getting legislation approved to provide compensation for victims of contaminated drinking water at Camp Lejeune.
Miller planned to meet with reporters later Thursday to discuss his decision.