Buckner had a long career in the Cherry Creek School District and served as chair of the House Education Committee. He and sponsored a major bill earlier this year to reduce student testing.
"He was incredibly passionate about addressing the achievement gap and ensuring that regardless of what neighborhood you come from and what color your skin is, that you have the same opportunities to succeed in Colorado," said state Rep. Brittany Pettersen, who stepped in to head the committee after Buckner took leave.
Buckner was 67 years old. His seat will be filled by a Democratic vacancy committee in the coming months.