Did he say in 2007 that these reforms are a Trojan horse for a single payer system?
I believe he expressed an opinion- just as he expressed an opinion about troops in Iraq and lots of other topics. Just as Bush expressed his opposition to abortion, for example. Whether a President is able to or even tries to implement such preferences is a different issue.
As an aside: while it is true that many insured people rely on their employer's scheme, why do comments about moving away from employer-funded schemes necessarily equate to moving to single payer? How did it come about that employers are responsible for employees' healthcare needs in the first place, and why is such a socialist concept seen as a virtue to be defended? Who does it benefit and why?
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
