TICK tock, tick tock.

Federal emergency officials have been given 15 minutes to respond to local calls for help or they will answer to the commander-in-chief. Tick tock, tick tock. The priority is to get the lights back on. Tick tock, tick tock. But as fast as the White House is reacting, people must not forget that this is going to be a long haul. Tick tock, tick tock.

Time is obsessing President Obama, as well it might. As America stumbles, dazed and disturbed, from Hurricane Sandy's battering, he is facing the greatest test of his presidency, and this is a President who, outside of his battle for health care reform and the capture of bin Laden, is not used to feeling the heat. Just to add to the pressure, he's up for election next week.

When Mr Obama was fighting Hillary Clinton for the Democratic nomination in 2008, there was much talk of the "3am test". In short, who would you most trust to take that dreaded wee-small-hours call about disaster and respond best? Mr President, this is your 3am wake up call.

Both the President and Mitt Romney, his Republican challenger, were back on the campaign trail yesterday. This was never going to be campaign business as usual, however. An election that has already surprised some with its closeness now has a few more variables in the mix. Mr Obama is having to put his credibility on the line just at the time when many Americans doubt he has four more years in him. Can he prove them wrong in four days? Or will Sandy claim his presidency as another casualty? Sandy is an October surprise like no other.

So far, the President has done everything right, the symbolism has been spot on and the polls agree he is doing a good job. The opening bell has rung again on Wall Street, the airports are inching back to normal, some New York subway trains are moving. He has even earned praise from Chris Christie, the Republican governor of New Jersey, the state worst hit by the storm. Previously a doughty critic of the administration, he praised Mr Obama's response as "outstanding" and said he didn't "give a damn" about presidential politics right now. In that, he spoke for those poor souls contemplating the loss of their loved ones and homes, be they on the east coast of America, where the death toll has hit 80, or the Caribbean, where it is at least 70.

Others need to care, however. This could be the closest race since Gore versus Bush, and just as pivotal. Whatever else happens between now and next Tuesday, Mr Obama can at least content himself that his initial reaction to Sandy is outstanding compared to the Bush administration's shameful response to Hurricane Katrina. Had Katrina happened a year before, George W Bush would not have had such a stroll to a second term (or at least one would like to think so). With Sandy, the system of early warnings worked in as much as the death toll would have been far higher without them.

Calamity can make a leader. Witness Mr Bush, again, after 9/11. See Mrs Thatcher and the Falklands; FDR and the Great Depression. It can break them, too, as Jimmy Carter found out with the Iran hostage crisis. At its most basic, the relationship between governed and the governors is a primal one. Those who are seen to fail the most basic test of keeping their people safe from harm, or who are unwilling or incapable of responding successfully to such a test, are damned at the polls.

In one sense, Mr Obama is the perfect president for days when the New York subway becomes a fast-flowing river and salt water pours into the still-gaping wound of Ground Zero. Sarah Palin, the Republican attack dog, once derided him for spouting all that "hopey, changey stuff", yet that is just the kind of thing people standing in the ruins of their homes need to hear. When Mr Obama says: "We don't leave anybody behind", echoing the US Soldier's Creed, he speaks directly to America's sense of itself as one family under God.

Crucially, however, Mr Obama has to balance the speeches with solid action. It is okay not to have the lights on the day after one of the greatest storms in living memory. But it certainly will not be okay if that is still the situation for millions come Sunday. A President who has struggled to get things done in DC now has to show that, in the words of his old campaign slogan, he can actually fix it in the real world.

For all these reasons and more, the storm is widely seen as more of a setback to Mr Romney's hopes than Mr Obama's. Not necessarily. As was seen in that first, game-changing television debate, cometh the hour, cometh the statesmanlike, moderate Mr Romney. Yes, the media is more interested in pictures of floating yellow taxis than running yet another speech by Mr Romney, but every news bulletin that features the plucky hopeful packing food parcels is one less discussion of his views on abortion, social security reform, Iran, or many another contentious issue. Being at a low peep suits Mr Romney's purpose.

This election will be, and always has been, about three things – winning over the minority of undecideds, getting out the vote, and answering the question America always asks itself: do we want big government or small? In each case the storm will have an effect. Mr Obama and Mr Romney's responses could tip the undecideds towards a choice (and it may not be Mr Obama). The famed Mr Obama get-out-the-vote machine will be even more crucial when people are disinclined or unable to travel to polling stations.

It is the answer to the big government question that is the biggest known unknown of all. Although it has not affected every part of the US, the hurricane has been a humbling force for all of America. The richest nation on Earth, once again, feels what it is like to be vulnerable. After terrorist assaults, economic crisis, deep and angry divisions over social change, America is at that fabled crossroads once more. Does it carry on with the man who promised change but didn't deliver much of it, who believes in big government as a force for good, or does it head right with the candidate who says he means business in every sense and wants government to start working or step back? Tick tock, tick tock.