Why don't they or haven't they gone out and get the 86000 signatures and get the thing on a general vote? There is at least 1 per year for something. I myself think it's stupid that it's even something to vote on let alone them wasting time on. I do however find it very suspect that it's all of a sudden become an issue at the POTIS level. If he felt that way before why wait until now?
The grassroots effort in colorado is woefully inadequate and it just hasn't been a ground for organization, yet. After this loss, you will see more organizations springing up and more visibility to the issue and more push for a vote. It's far easier to get something to pass in the legislature in the marriage equality favor than for general public vote, which is why the efforts have been directed that way.