The Colorado State Senate has 35 members and is the upper house of the Colorado General Assembly.

Since 1975, the presiding officer of the Senate is the President elected from among the body.

From 1876-1975 the presiding officer of the Senate was the President Pro Tempore elected from the body.

From 1876-1975 the Lt. Governor served as the President of the Senate and served as the presiding officer of the Senate until the Senate organized after the opening of a new session when the President Pro Tempore was elected by the body.

Senators are elected to four year terms.  17 districts in one election cycle, 18 districts in another election cycle.