er, uh, I was never very good at biology. I think it means something like, shaky, about to topple and may have nothing to do with , except the kind in the media.
Just joking....I really do know what teeter means. But really you're right, "teeters on the brink?" Reminds me of a CNN guy a year or so ago talking about gay men and marriage. He said something like, "For now they are considering a backdoor approach." !!!!!!