Gov. John Hickenlooper has 15 days to appoint one of the nominees.
Allison Eid replaces Neil Gorsuch who is now a U.S. Supreme Court justice. Gov. Hickenlooper will choose Eid's replacement.
The court will review a Colorado court decision that found baker Jack Phillips and his Masterpiece Cakeshop discriminated against the gay couple under Colorado law.
But Bennet's vote won't stop Gorsuch's ascendance to the Supreme Court after Republicans deployed the "nuclear option" earlier Thursday.
The man chosen by President Donald Trump to fill the Supreme Court seat vacated by the late Antonin Scalia is a fourth-generation Coloradan.
Neil Gorsuch has spent a decade on the Denver-based 10th U.S. Circuit Court of Appeals, which hears disputes about public lands across six Western states.
Judge Neil Gorsuch has said deferring to agencies is an abdication of judicial responsibility. He is expected to be grilled on this at Monday's confirmation hearings.
Neil Gorsuch, who sits on the U.S. Court of Appeals for the 10th Circuit in Denver, is considered a conservative and an originalist, who tries to adhere to what he believes the framers of the constitution intended.
The 49-year-old Gorsuch has served on the 10th U.S. Circuit Court of Appeals in Denver since 2006, after being appointed by President George W. Bush.