A FAVOURITE quotation used by writers about politics is traced back to Harold Macmillan, the onetime Tory Prime Minister. Asked what his biggest problem was, Macmillan is said to have replied: "Events, dear boy. Events."

Despite being attributed rather than traced directly to Macmillan's lips, these words have lasted down the years and fit the moment. As Tony Blair suffers his most embattled time to date as Prime Minister, he might, were he asked the same question, reply: "Momentum, dear boy. Momentum."

It is interesting to watch these periods, when events turn against a politician or a party. There is a sort of madness in the air and a lot of what is written or spoken passes more or less for virulent nonsense; yet the more these gossip-garnered words are written down or reported over the airwaves, the greater the momentum becomes, until the gathering speed is unstoppable.

Each episode in political history is different, although political commentators still scavenge the past, rummaging for clues.

So it is that Tony Blair has been compared to Margaret Thatcher in her on-and-on "mad old bat" mode. The crueller cartoonists have long linked the two premiers, giving Blair the frenzied, wonky-eyed stare and the look of frazzled intensity.

This is caricature at its worst/best, depending on preference - exaggerated, crude and yet based on a certain truth, or a guess at the truth. Guessing is the way the game goes and this is certainly a game. Most commentators don't know exactly what is going on but they have exciting scraps to wave in the air, little sticks of rumour and conjecture to build into something more robust.

The participants in this game are: the politicians; the media; and the paying public.

The punters are not involved as such, at least not at this stage. Our say will come later with a general election. For now, all we can do is sit back and watch the show, cheering or shuddering as prejudice takes us.

That leaves the politicians and the media, locked in the over-heated hot-house world of Westminster, where rumour sprouts at a fantastic pace.

In some ways, the politicians and the national media deserve each other. They live together in a state of mutual distrust, hating each other but unable to live apart. Divorce is often mentioned but nothing happens because it is that sort of a relationship; perhaps the sex is particularly good.

Tony Blair has been the victor in all this and now he is the victim. Quite why he has fallen so far is complicated. Some of the recent reporting in Blair-hating national newspapers has been self-righteous and arrogant stuff, in which the editors and their owners have staggered under the weight of their own importance.

So it is that last weekend's Mail on Sunday could boast a tombstone headline declaring: "Blair told: go now", all based on its own survey of 25 Labour officials in marginal seats, of whom five - yes, just five - offered the opinion chiselled into the front page.

There has been much more, of course. The never-ending rumours of the rift between Blair and Gordon Brown; calculations about whether Brown would make a better PM; and the rose-tinted speculation on how everything would have been all right if only John Smith hadn't had that heart attack.

In all this, Tony Blair is partly a victim of the vicissitudes of politics and life, in which you are up one day, down the next.

Newspapers, especially national titles with top-heavy political agendas, love to kick a man when he is down. It helps if they are filled with envy and loathing for their victim. It is not a pretty sight.

In the end, most of this has to be traced back to Blair himself. By trying to please everyone, by twisting this way and that, by showing this face to that person and another to the next, he has left people resentful or at best confused.

He has done much right, especially in relation to alleviating childhood poverty, trying to sort out the NHS and presiding over a buoyant economy. Yet his determination to join in America's Iraq war looks increasingly likely to haunt his remaining days in power.

If the momentum got him tomorrow, the horrendous mess in Iraq would be his biggest legacy. That wouldn't be fair, but fairness doesn't come into it.

Updated: 11:03 Thursday, May 20, 2004