The president stammers because he thinks too fast.
I don’t recall Buckley as a stammerer, just a deliberate speaker. It’s been a long time since I heard him, though. And I do find Obama’s long “aaaaaannnddds” annoying. Of course, I think that Sarah Palin needs a speech coach, too, not to get rid of her accent, but to lower the register of her voice a little and not sound quite so screechy.