Leading article: Storms amid the sunshine

Apart from the wretchedly unlucky people of New Orleans, one other large group of Americans is looking at the storm bearing down on them with particular dread – the Republicans. With awful timing, Hurricane Gustav is due to hit the Louisiana coast on the day the Republican convention opens in St Paul. As Minnesota lies miles from the impact zone, the convention itself faces no danger. But a potential natural disaster is the last thing John McCain needs as he tries to recapture public attention following Barack Obama's oration in Denver. It reminds Americans of the Bush administration's dismal handling of Hurricane Katrina.

The chink in the dark for Mr McCain and his surprise choice as running mate, Sarah Palin, is that George Bush may not now show up in St Paul at all. This may be no disadvantage to a Republican candidate seeking, as Mr McCain is, to put the widest possible gulf between himself and the current unpopular incumbent of the White House.

Certainly, thus far, the Arizona Senator has performed well, chipping away at Mr Obama's lead to the point where the remarkable possibility presents itself that the Republicans could retake the White House in November. With the Democratic candidate leading by only a couple of percentage points in the polls there is everything to play for – especially given the Republican's fondness for the politics of destruction.

The bold choice of Sarah Palin as running mate, meanwhile, is just the kind of high-risk move that Mr McCain delights in as proof of his maverick nature. True, he may regret the day when he picked a political ingenue who only two years ago was mayor of a small suburb of Anchorage. Equally, it could turn out to be a master stroke. Fiercely evangelical, anti-abortion and pro-hunting, she is precisely the right kind of political partner to shore up Mr McCain's support among the party's important evangelical constituency. And one suspects that a Republican star has been born.

Mr McCain's chances of overtaking Mr Obama before November now depend on the continued success of the "surge" in Iraq, and signs of progress on the economy and housing market. It seems a long shot, but Mr McCain has been lucky before, and may be again.