The aftermath of superstorm Sandy has produced one of the strangest political pairings of the year, bringing together Barack Obama and one of Mitt Romney's most prominent supporters, Republican governor of New Jersey Chris Christie.

The 50-year-old governor has emerged as the public face of the storm: energetic, emotional and efficient, a seemingly permanent presence on television screens over the last few days. Already well-known in the political world, he is now a national figure.

With Sandy still too raw for anyone to start make political points, there has been no backlash from Republicans about his alliance with Obama only six days from election day. Christie has said politics do not matter to him at the moment. But on Monday, even before Christie lavishly praised the president's handling of the storm as "outstanding", the right-wing talk-show host Rush Limbaugh called the governor "fat" and "a fool".

Christie was a keynote speaker for Romney at the Republican convention in Tampa this summer and has been out on the campaign trail regularly on his behalf. And yet he not only praised Obama but, unlike mayor Michael Bloomberg in New York, also agreed to host the president on a tour of the stricken parts of his state.

So what is going on? Has Christie secretly harboured a grudge against Romney and grabbed the opportunity to try to sink his campaign? Or is he just being pragmatic, thinking locally, looking for maximum federal aid from Obama?

One scenario is that although Christie has loyally campaigned publicly for Romney he privately does not really like him much.

Evidence for this? When he delivered his keynote speech to the convention, delegates had anticipated a rousing build-up of Romney and a demolition job on Obama. In the end, in a televised address watched by tens of millions, he barely mentioned Romney, did not mention Obama at all and spoke mainly about himself.

In all the interviews that Christie has given over the last few days, his response comes across as mainly emotional, the guy from Newark, New Jersey, overcome by the destruction of the beloved shoreline he knew from his youth. It could be as simple as this.

The most Machiavellian of the scenarios is that Christie, who was pressed by many Republicans to stand for the White House this year but declined, is thinking that if Romney was to get elected next week, Romney might then go on to win again in 2016. Christie's first crack at the White House would then be 2020 and, given the normal tendency of the electorate to give another party a chance, he might be facing a strongly favoured Democrat. Better for him that Romney fails next week, leaving the way open for a Christie run in 2016.

If the Republicans lose next week, they might just decide to move to the centre and that is where Christie has positioned himself, to the left of the present-day Republican party.

The final and most plausible of the scenarios is that Christie is thinking not about 2016 but 2013 when he faces re-election for governor against a potentially strong Democratic field, of whom Newark mayor, Cory Booker, a strong orator, is favourite to face him in what is a traditionally Democratic-leaning state.

It could be that, like all politicians, Christie holds in his head all these scenarios, emotional about the distress and damage before his eyes, and pragmatic too, but also thinking strategically to next year or even 2016.