Buckle up because Barack Hussein Obama has just stumbled upon his old self, the man America fell in love with in the 2008 election race – the one who invoked Martin Luther King Jr, telling voters he would be driven as President by "the fierce urgency of now". Remember that phrase that offered such promise and passion?

We celebrated when he decreed the closing of Guantanamo Bay and promised to end the bi-partisan gridlock of Washington. We looked forward to his passing immigration reform and getting serious about climate change. Then Congress bogged him down and he grew timid.

Flickers of the old Obama who once thrilled us returned this year when he confessed his conversion on gay marriage and removed the threat of deportation from millions of young undocumented immigrants. Then he clobbered Mitt Romney and with re-election, got a second chance. He can't run again, of course, so are the fetters now off?

The trouble is that while they botched winning the White House and taking control of the Senate, the Republicans easily held on to the House of Representatives. Mr Obama does not have a free hand on passing new laws. Yet he won in November by a decent margin and surely he is stronger now than six weeks ago. You see it in his rising approval ratings – up to 55 per cent now – and in the defensive Republican posture in the negotiations to avoid new tax hikes and spending cuts.

Of course the quicksand could return quickly, particularly if the progress we think we see now on averting that dreaded 'fiscal cliff' falls apart. But if you watched Mr Obama give his speech to the inter-faith service in Newtown, Connecticut, on Sunday night lamenting last Friday's school massacre, you may have sensed what I did. It elicited sobs in that high school auditorium. My guess is that it drew tears in front rooms all across the land.

Whence has come that new power in the loins of the leader? Clearly, it had partly to do with the issue at hand – the slaying of 20 young children. Friday, he had said earlier, had been the hardest day of his presidency. Now that it is about children, the fight for gun control is not just a priority, it is an imperative.

The President is stronger too because the mood among Republicans has changed. After Mr Obama won the first time, the top Republican senator, Mitch McConnell, said denying him a second term should inform everything his party did. There's no need for such belligerence now. Republicans' hopes of winning back the White House in 2016 need not be dashed; Clinton Part II went well yet Al Gore lost in 2000.

So here's to the new, old Obama. It may be hoping for too much, but the next four years in US politics could be as exhilarating as that 2008 campaign.