An identical measure, Amendment T, failed by a narrow margin in 2016 possibly due to unclear wording on the ballot. This time around, supporters have tried to make ballot language clear that a “yes” vote means “abolishing slavery” and a “No” vote keeps slavery in the state’s constitution, Emery said.

Voters in 2016 also had concerns that the amendment would make prison work and community service programs unconstitutional. Such work programs are not affected by the amendment because they are voluntary, said Will Dickerson, formerly of the Denver nonprofit Together Colorado, in a 2016 interview with CPR News.

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