Democrats seeking this year to install sweeping new union rights for hundreds of thousands of Colorado public employees are up against a familiar obstacle in Gov. Jared Polis, and they’re in talks about scaling back their bill to get it passed and signed into law. What they want to do is confer the right to unionize and collectively bargain upon firefighters, teachers, snowplow drivers and other workers across the public sector, where labor rights are fewer than in the private sector.