John Rentoul: We're more negative about politics than ever. (I expect it's all Tony Blair's fault)

Clarke muffed his chance to offer his critique of the PM

"Personal attacks and negativeness": that is what is wrong with politics today according to David Cameron. Or at least that is what he says went wrong with the by-election campaign in Bromley, a safe Conservative seat he nearly lost to the Liberal Democrats. He is on to something. Popular attitudes to politics are now more negative than they have been at any time for 30 years. No doubt it is all Tony Blair's fault. Most things seem to be. But this "negativeness" could be the hangover from Blair's extraordinary popularity, apparently insubstantial yet slow-decaying.

The Prime Minister once rated as doing a "good job" by 93 per cent of the electorate is now reviled and distrusted. Yet those who seek his crown are barely better regarded. Gordon Brown is seen as a little more decisive, effective and trustworthy, but questions in opinion polls about how people would vote if he replaced Blair only depress the party's standing. And Cameron was only barely preferred to either of them as "best prime minister" in last week's YouGov poll.

The Bromley result confirms that Cameron's Conservatives are a long way from generating any excitement about the prospect of getting rid of a Labour government that is widely, if unfairly, seen as tired and directionless. By-elections have, since 1962 when Eric Lubbock won Orpington, next door to Bromley, been a chance for voters to remind a government who pays its wages. That is what the voters did in Blaenau Gwent, although Labour managed to claw back a surprising number of votes lost at the general election.

What Bromley suggests is that by-elections are a chance not just to protest against the Government, but to vote against "politics" as a whole. Worryingly for Cameron, he is regarded as part of the established order, not an alternative to it. Despite the greenery and the baby sling, the Tories in Bromley did not attract Liberal Democrat voters. Despite Menzies Campbell's absence of leadership, voters still saw the Liberal Democrats as the most effective vote against the system.

The contrast with the years of the Blair insurgency is unflattering to Cameron. While Blair was leader of the Opposition, there were three by-elections in Labour-held seats. While a 14-point swing against the Tories in Bromley cut their majority to 633, the biggest swing against Labour was 7 points in Islwyn in 1995, which brought Plaid Cymru to within a mere 13,000 votes of Labour's Don Touhig. Of course, that was before Labour won a general election by the biggest margin in modern two-party history. The result in Bromley is still consistent with Cameron winning a normal majority, or leading the largest party in a hung parliament.

The main lesson of last week's by-elections, then, is the lack of enthusiasm for any of the three parties and four leading politicians jostling to get their message across. The negative climate is partly due to the apparent shrinking of the possibilities of politics since the early Blair years. Yet it remains completely unclear what is wrong with Britain under the Blair government that either Brown or Cameron can put right.

Hence perhaps the interest in other possible political directions. But Charles Clarke, the former home secretary, muffed his chance to offer his critique last week - which was a pity because he is not a trivial politician. His general criticism was vague, that Blair had lost a "sense of leadership and direction", and the specifics amounted to little more than: "How dare he accept my resignation?" He also repeated the common misrepresentation of his successor, John Reid, as describing the entire Home Office as "not fit for purpose" when the words were applied to its Immigration and Nationality Directorate. In any case, it was a bit rich for Clarke to complain because, two weeks before he was sacked, he had said in the Commons that he "completely agreed" with the Labour MP John Spellar that "the Home Office is a seriously dysfunctional organisation".

All Clarke succeeded in doing was to confirm Blair's judgement about the reshuffle in which he lost his job. Last week the Home Office put out the latest update on its attempt to round up the 1,000 foreign prisoners that had been released without being considered for deportation - the issue that forced Clarke out. It suggested slow and uncertain progress, with many of the numbers "rounded to the nearest five", an unusual convention of statistical imprecision. Yet the figures were reported calmly, and the fact that one prisoner had gone on to commit murder treated unsensationally - the fact that he could not have been deported anyway, as a pre-1973 citizen of Ireland or the Commonwealth, seemed to satisfy even the Daily Mail. Imagine how different that would have been had Clarke still been in post.

I don't want to add to Clarke's sense of hurt, but I also think Reid has done well in the short time he has been in the job. He has been roundly thrashed by the stern overseers of the liberal press for (a) criticising a judge for a lenient sentence and (b) pandering to the anti-paedophile hysteria of Megan's Law. In both cases, Clarke said he wouldn't have done it. In both cases, Reid was right and the liberals wrong.

A home secretary should take people's fears for children's safety seriously, even if popular attitudes are riddled with misconceptions. The way to reassure people is not to dismiss their concerns. I am sure Reid knows as well as anyone who has looked at the evidence that the idea of publishing names and addresses of sex offenders would be counter-productive, but if that is what the evidence suggests, who can object to looking at it again?

The Clarke approach, on the other hand, seems calculated to increase people's distrust of and alienation from politics. The idea that the elite should tell people that their fears are based on ignorance, or that judge-made law should be accepted when it offends a common sense of fairness, is a foolish one. Most baffling is the press hoo-ha against Reid and Blair for provoking a "constitutional crisis" by attacking the judiciary. This is nonsense: if the judges interpret the law in a way that politicians did not intend, the politicians should change the law and ask the judges to enforce it. That is not a crisis, it is how the constitution is supposed to work.

That is the paradox of the "negativeness" of politics. Between Blair, Brown, Cameron and Campbell, the one politician most strenuously trying to bridge the gap between people and politics is the one who is not standing at the next election.