True. Although it seems to me with his huge whole "the day after the election I turned into a fiery liberal" stint he'll veto it on since he's now the world's #1 environmentalist. Also, with gas prices dropping, that probably lessens any severe public outcry.
IIRC, All Obama has been about with Keystone is about "reviews, reviews and more reviews," trying not to take a stance at least pre-midterms. It will be interesting to see what he does when the Keystone XL Pipeline bill passes in the new Congress.
Republicans should be four or so votes away from an override in the Senate and would probably need to find 30-40 votes in the House. Unlikely, but you never know.