A legislative committee has given initial approval to a plan that would allow Colorado pharmacists to bypass doctors and prescribe emergency contraception.
The vote came despite objections from Republicans who said the change would set a dangerous precedent.
Officials with the Colorado Gynecological and Obstetrical Society say doctors expect the "morning after pill" to win federal approval to be sold over the counter.
The bill now goes to the full House.
Alaska, California, Hawaii, Maine and New Mexico have made the drug available without a prescription.
Four other states Arkansas, Georgia, Mississippi and South Dakota have passed laws allowing pharmacists to refuse to fill prescriptions for emergency contraception.