Actually what has happened to Colorado is rather more complicated. There are two main factors which have screwed up Colorado politics:
A) Californians fleeing their debased state. Of course those morons then come to Colorado and try to institute the same crap which brought their state down. Lucky us.
B) Tim Gill. Ironic that I have to state only one name eh? Well a number of years back Colorado passed an amendment which stated that Gays would not be a protected class. Eventually this was thrown out by the courts. However this upset Mr. Gill (a founder of Quark, the desktop publishing software company) who happens to be light in his loafers. He then decided to change CO politics by himself by blowing his massive fortune on the cause. He flooded every election in CO at all levels with donations completely throwing things out of what. Local elections which might have had an aggregate spending of 10s of thousands of dollars now had 100s of thousands being spent on the Democrat side, and it had a marked effect. Every level of CO politics took a leftward tilt because of this interference. Gill has spent 100s of millions on this so far, and honestly money sure has talked.
I moved to Colorado partly because it was a good conservative western state. Gill and the CA crowd has been stealing it out from under the conservatives.
Don't forget Pat Stryker and all of her evil inherited wealth, fellow homo Jared Polis who goes through life using his mother's maiden name and Rutt Bridges.