In today's partisan politics, unless we have just been attacked as a country, I don't care how large the margin of victory, the losing side just isn't going to compromise thinking there was a mandate in the election.
It could be argued that the sweeping victory by Republicans in the 2010 mid term elections was a mandate for the President to compromise with the Republicans. That didn't happen.
I just think the ideologues have firm control of too much power in Washington and its killing any chance at compromise from either side.
I agree generally but I will say that if Obama had won by say, 20 million votes instead of 5, the Republicans would feel a lot more internal pressure to adjust what they're doing.
I think it's important to distinguish between the "mandate" talk, which is mainly a public PR battle about how obligated the losing side is to compromise, and the mostly private strategy shift that always accompanies a loss and is much more directly related to the specifics of that loss.
I think it's safe to say the GOP is much more alarmed about the election loss in private than they're willing to show in public, which is why a lot of politicians are downplaying it, and political strategists are practically banging pots and pans together while screaming for adjustment.