@engineer,
I agree about the distraction.
But I do think this is a big deal. The "oops" can be inserted in any number of attack ads and is a great shorthand for him being not that smart and not ready to take on a job as serious as President of the United States.
He was already floundering and this is the kind of thing that by itself would not be good, but in a different context wouldn't necessarily be that bad. An obviously smart and prepared candidate who just had a momentary brain fart, for example.
But this fits right in to the negatives he was already developing and fighting against. It amplifies them all.
Plus it's the kind of thing that goes on the front page of Yahoo news, that the late-night people are probably going to have a field day with, etc. It's the sort of thing that goes beyond the chattering class and helps define a candidate to people who don't follow all of this that closely.
It can be flogged to death, and that might happen. If it does, then there could be a backlash. ("It wasn't
that big of a deal! He's a regular guy.") But it looks pretty bad right now.