The choice of venue to unveil it on 10 June was notable: the American Enterprise Institute, a top conservative think tank in Washington. The Democrat co-sponsor of the 37-page American Opportunity Carbon Free Act , Senator Brian Schatz (Hawaii), admitted: “I never expected to be here,” adding “let's begin the discussion”. An environmental NGO would have been a more obvious choice of venue to launch the bill, however some conservatives do support a carbon tax, seeing it as a less…