CO · State rules
Colorado
Primary system
Open to unaffiliated
Who can vote in a party primary
Unaffiliated voters may pick either party’s primary; registered members locked to their party
Party-switch deadline
22 days before the primary election
Note: Strategic option: registering unaffiliated preserves cycle-by-cycle choice.
This cycle's dates
Next primary
Tuesday, June 30, 2026
Party-switch deadline
Monday, June 8, 2026
Registration deadline
Monday, June 8, 2026
Computed from the standing rule + NCSL's 2026 primary calendar (fetched 2026-07-27). Not yet checked against the official state source for weekend/holiday rollover or this cycle's final confirmation — verify before relying on it.
Verification pending Last checked: 2026-07-27
Draft sourced from NCSL. View source.