Leading article: Mr Blair must prove that he still has something to offer the country

The Prime Minister likes to joke about the bad weeks he has experienced, but the one just drawing to a close must count as one of the worst. Quite how bad it was can be judged by the extent to which Mr Blair behaved out of character and how many concessions he had to make. At Thursday's press conference, his customary confidence and fluency deserted him. Suddenly, he was not the media-master of all he surveyed. The questions got under his skin; he looked hot and bothered. He hesitated; he searched for words. It was not that he offered no plausible explanations. It was that he hardly tried.

Within 24 hours, he had also made a series of concessions that he would clearly have preferred not to make. First, he appointed a retired civil servant as an independent arbiter to consider matters such as potential ministerial conflicts of interest. This was a recommendation from the Committee on Standards in Public Life that Mr Blair had accepted in principle several years ago, but had then never acted on.

At the same time, Mr Blair proposed cross-party talks on the funding of political parties, something else he has resisted. He also said that he would renounce the right personally to nominate people for honours. Finally, the Labour Party revealed how much money it had received in the form of commercial loans from wealthy individuals before last year's election. At almost £14m, the figure was larger even than the most speculative figures that had been bandied around.

It is very hard to believe that Mr Blair did any of this willingly. It is equally hard to believe that any of this would have seen the light of day without either the public frustration of Dr Chai Patel over the block on his peerage or the fury of the party treasurer, Jack Dromey, on the matter of the loans. Mr Blair, it seemed, was no longer in control of the script.

In isolation, either one of the current scandals - loans for peerages or Labour's circumvention of the disclosure rules on party funding - would have been damaging enough. That Mr Blair was violating the spirit, if not the letter, of disclosure rules on funding, which his own government had introduced, only added an extra ironic dimension. But they were not isolated instances. They tapped into areas - the appetite for money, the hobnobbing with the wealthy, the politics of peerages and the "spinning" of facts, in this case, the party's accounts - where Mr Blair and New Labour have form. This is why the claims were not only believable, but especially detrimental as well.

They had the effect of magnifying the significance of other recent events: the vote on the Education Bill earlier in the week, which the Government won thanks only to the Conservatives and the continuing resistance in the House of Lords to a key provision in the legislation on ID cards. They also revived memories about the Jowell-Mills fracas that had appeared to be fading. And through everything could be heard the stubborn drumbeat from Iraq: the war, almost three years old, that will haunt this Prime Minister's reputation for ever.

Altogether, Mr Blair emerges a weakened leader, a hostage to the reopened schism between New Labour and Old, dependent on the re-energised Tories for passing legislation he sees as his own, harried by media hounds with their keen sense for vulnerability. This does not mean that the New Labour agenda is exhausted. It does mean that the Prime Minister will have to convince MPs and voters that it still has something to offer. This week's Budget presents both a chance and a test. If Mr Blair lacks the appetite for it, the time may be approaching for him to call it a day.