John McCain's statement that he will temporarily withdraw from the Presidential election in order to focus on pushing through the urgently needed financial package to stabilise the US, and by extension, the Global economy, is something I still can't get my head round.

It's like a cut diamond held to the light; turn it around and the beam it casts changes.

What he's done, smacks of honour and does obviously underline his"country first" message. It is an act of selflessness, and from what I know of him, in line with many of his previous actions.

Yet, he is a politician, who as a breed are different to us in so many ways; the lure of a quick, showy victory is like catnip. Irresistible. I remember William Hague once saying that he would only ever talk on the topics of the day, which I've always understood as a less than intelligent excuse to exploit something without properly thinking the consequences through, in other words, opportunism.

It's opportunism that I think could be driving John McCain - be see to be doing something, act and look Presidential, even if the anointing has n't even happened, and may not - the electorate has n't cast a single vote yet.

When I rotate my cut diamond through the light I sometimes see something else: desperation. Turning the spotlight back on to his campaign not through the hard work of selling proposals and policies, traditional, austere, unflashy campaigning; it's sturm und drang gesture instead. Take Sarah Palin as his VP nominee for example.

I do like McCain - it's an extraordinary personal story. As much, though, as I admire him, there's this sense I get that he's really an impulse purchaser, tacking to every different breath of wind, and not setting a defined course and holding to it. That worries me.

It's his impulsiveness that I find unsettling. This is a serious world we live in: issues are subtle in detail, complex and nuanced, not black, not white, but grey, and difficult to unpick; there's a need for detailed scrutiny and thinking through, and not imprudent, hasty, on the hoof decision making.

How strange that of the two candidates, it is the younger Obama, who looks to possess the gravitas necessary to fulfilling the most demanding of all Chief Executive posts. For me at least he does. It's up to the US electorate to ultimately decide.