Chris B, winning an election does not a "mandate" make.

First off, when almost half of the voters preferred someone else, you clearly don't have overwhelming popular support.   Even if you get 60% of the vote, that's only considered a "landslide" because it's such a rare occurrence in US politics. You still have 40% of the voters who preferred someone else.

Secondly, you can't tell from the mere vote totals why people voted the way they do. There are "single-issue" voters, who will back a candidate they agree with on ONLY that one issue (e.g, gun rights, anti-abortion legislation).    A candidate, such as Obama, can lose support because: a) people prefer more "conservative" policies, b) people prefer more "liberal" policies, or c) they have been misled about the candidate's policies, platform, accomplishments, etc.

If you want to know what "message" the people are sending, do some good, non-partisan, scientific opinion research.   INFORM them, insofar as that's possible, about what the various legislation would and would not do and then ASK them, not just whether they approve or disapprove, but WHY.