Feel free to Google for other articles that state the same, but the overall point is that: People that claim that Sanders' views are widely supported are not at all indicative of what will translate to the voting booth.
That may be true---actually, I think it probably is. But that has nothing to do with the extremely bleak and cynical statement you made:
> Most of America is for the ACA, but against Obamacare, it all depends on how you phrase the question
which, fortunately, appears not to be the case.
If this is the source of the claim---and it appears that it probably was---the claim is a serious mis-statement.