Brad Freedburg is out. I'm not sure about Larry Johnson as he withdrew and then rescinded his withdrawal. That pretty much leave Mike Miles as the only candidate eligible for the democratically selected nomination process - ie, precinct caucus/county assembly/state convention.
Salazar will have to buy his way into an August primary by collecting a minimum of 1,500 valid signatures from registered Democrats in each of the 7 Congressional Districts between April 5th and June 1st. At that point, it's up to the Secretary of State to verify those signatures and certify that Salazar can run in the primary. At this point, technically, he's not even a candidate.