A vote on the House proposal, sponsored by Democratic Reps. Claire Levy and Jovan Melton, was delayed Tuesday night after nine hours of emotional testimony, The Denver Post reported.
Several victims' families, as well as faith-based leaders and even a former death row inmate, packed into a committee room to speak in favor of the repeal.
Lawmakers previously attempted to repeal the death penalty in 2009, but failed by a single vote, the newspaper said.
The bill would not impact the three men already on death row, or someone charged with a crime before the law is enacted, the Post said.
If passed, the maximum allowable sentence will be life without parole.
Arapahoe County District Attorney George Brauchler said repeal of the death penalty would make it more difficult to find justice in the worst of cases.
Brauchler's office must decide by April 1 whether it will seek the death penalty against James Holmes, the man charged with killing 12 people and injuring 58 others in a movie theater last July.