"Are Americans really so petty..."?
Yes, they are. At least 60% are. There were what...51% voted for Obama. Another chunk that are registered and didn't vote but my guess would vote for Obama if forced to choose, and another bunch that aren't registered to vote--whether they are citizens or not. I'm guessing most of those would vote Obama.
This country has gone full circle. John Adams said of the people at the time of the Revolution that 1/3 support the cause of American freedom and independence, 1/3 oppose and 1/3 don't care. The same now holds true again.