Colo. Const. art. V, § 22a

Caucus positions prohibited - penalties. (1) No member or members of the general assembly shall require or commit themselves or any other member or members, through a vote in a party caucus or any other similar procedure, to vote in favor of or against any bill, appointment, veto, or other measure or issue pending or proposed to be introduced in the general assembly. (2) Notwithstanding the provisions of subsection (1) of this section, a member or members of the general assembly may vote in party caucus on matters directly relating to the selection of officers of a party caucus and the selection of the leadership of the general assembly.