A Spoiler is:

A non-winning candidate whose presence on the ballot affects which candidate wins.
The Spoiler Effect  displays the failure of the present Choose-one Plurality voting method in Colorado by terms known as Independence of Irrelevant Alternatives. Approval voting and range voting satisfy the independence of irrelevant alternatives criterion.
Complete information and examples found below

Colorado’s newest party is seeking citizens of the state to register to vote as Approval Voting Party members.

The Approval Voting Party has been established in Colorado. On October 1st 2019 over one-thousand Colorado voters have registered as AVP which was founded in late 2018.

The second statewide convention will be held in Denver on March 1st 2020.

Voters naturally want to choose more than one.