The Sandy Hook shootings and resulting debate about gun control in the US may prove to be one defining feature of President Obama’s second term. Here, BBC North America editor Mark Mardell looks at what the news media and other US observers can expect from Obama’s next four years in the White House:
The leader of the Republicans in the House of Representatives, John Boehner, says what we saw just over a month ago was a "status quo" election.
He hadn't been plundering the iPod of his colleague and self-confessed heavy rock fan Paul Ryan, and listening to the Quo's early flop ‘Black Veils of Melancholy’, which might be appropriate for the Republicans right now. No, he meant nothing has changed.
He went on to accept that the President has been re-elected but, he said, so had the Republicans in the house - so it was a ‘no-one lost, no-one won’ sort of a draw. Up to a point, Lord Copper.
The President certainly doesn't see it that way. He believes he comes back with a fresh mandate - tax the rich, save the middle classes - and he's behaving as if he has had enough of trying to make deals with intransigents.
Many of his supporters seem to back him. But then many Republicans will back Boehner. In a recent opinion poll Republicans were asked if Obama won the election fairly or if it was ‘stolen’ by Acorn - a community organisation that campaigned for the poor and became a target for Fox News, which branded it extreme and corrupt. Forty-nine per cent said it had been stolen by Acorn.
Here's the rub: Acorn closed two years ago. So many Republicans are not just sore losers, they don't really accept they lost.
During the election both Romney and Obama agreed on one thing at least. They were offering two very different visions of America's future - and the election result would be a choice between two very different Americas.
In one sense the election produced concussion and the US is now suffering from double vision. A big question is whether it will remain that way or, over time, demographic realties or political choices clear the head and mean that a single vision emerges.
Understanding what lies behind this division of views is vital to interpreting what happens over the next four years.
US presidential elections are not unlike US TV dramas. As series one draws to a close you wonder if it is going to be re-commissioned. If not, you will be left unfulfilled, never knowing how the plot works out.
Well, there is going to be an Obama 2 and, having survived the election, we find the new series beginning in classic form - the protagonist on the edge of a cliff, just gripping onto the edge by his fingertips. And we'll leave him hanging there, on the edge of the fiscal cliff for a little while.
How that particular conundrum turns out will give an early clue to the answer to the question my successor is likely to be asking in 2016 : ‘What is Obama's legacy?’
All presidents ponder this and Obama may think about it more than most - from what we can tell, he sees himself as a transformational figure.
He wanted to become president convinced that change can only work when supported from the very top. Which raises perhaps the more intriguing question: what does he want his legacy to be?
A black swan could flap out of nowhere and change all the calculations, but there seem to be two different paths he could follow.
Part of what got Obama elected in 2008 was his promise to do politics differently. He made his name with a speech to the 2004 Democratic convention, saying: "There is not a liberal America and a conservative America - there is the United States of America. There is not a black America and a white America and Latino America and Asian America - there's the United States of America."
The best biography of him so far is called The Bridge. So Obama could try to be the conciliator, the man who healed America.
But he could also push his own agenda and that of his party. There are those who believe that in November the US took a decisive step down a more socially liberal path, towards a kind of American social democracy. Indeed many Conservatives would agree, although they would say America was becoming socialist, and ungodly.
It is possible he will fail at either; it is possible he will weave together the two paths. That would be a triumph, but the latter is more apparent at the moment.
During the election I said repeatedly that behind the two visions of America were two Americas. The ideological divide is very much sharper because the two visions grow out of two different coalitions - these are generalisations but they are true.
The Republicans’ supporters are overwhelmingly white, older, rural, fairly poor or fairly rich, southern and male.
The Democrats’ coalition is Hispanic and black - 45% of Obama's vote was from ethnic minorities, urban, younger and female.
Of course there are young black women conservatives and old white men who are liberals - but this is about broad trends.
One journalist has called the divide the brown versus the grey. Another has christened the Democrats’ alliance "the coalition of the ascendant" - and that is important. The conservative coalition is, quite literally, dying out. Those who make up the Democrats’ coalition will get more important over time. Liberal young people may turn into liberal old people, and Latinos will be increasingly important - one in four people under the age of 18 is Hispanic, and by 2060 non-Hispanic whites will be under 50% of the population, on current trends.
Now we can't say what party people will vote for in 50 years’ time. But we can say that nearly 50 years ago the Republicans adopted a strategy which alienated black people - the southern strategy, which targeted white voters in the south who felt abandoned by the Democrats. Many don't want to repeat that.
There are areas where the two coalitions and the two parties agree. They agree that education is the future but the system is in deep trouble. They agree the immigration system and tax system are broken; they agree that a 20-year decline in the income of the average American is deeply worrying. Agreeing on solutions may be beyond them. It would be ironic if Obama's legacy was a more divided America.