By Nick Assinder
BBC News Online political correspondent
This week was always going to be one of those "crunch" periods for Tony Blair's leadership that seem to come around with alarming regularity nowadays.
And the revelations that he had to be persuaded by friends not to stand down a month ago will only boost speculation in Westminster that, this time, it could be the real thing.
The political calendar always has the habit of mixing together big events into a brew that, once combined, can prove far more poisonous than the individual ingredients.
Speculation about Blair's future is growing
And so it is this week with the Chancellor's spending statement, publication of the latest Iraq inquiry and two losable by-elections.
And, once again, talk of the prime minister facing a pivotal moment has returned with a vengeance.
He has, of course, been on the verge of resignation previously, it is claimed.
He insisted himself that, had he lost the original vote on the war against Iraq, he would have gone. That claim came long after the event and critics claim he was only stating the obvious.
It is also claimed pretty authoritatively that he has more recently insisted he will quit if he becomes an electoral liability.
Such suggestions of resignation can work both ways. They can serve to focus the minds of any hesitant backbenchers who may be toying with the idea of joining the hardliners who desperately want to remove him.
Brown may boost leadership credentials
But they can also act as a signal of the prime minister's political mortality, and they whip up the already excitable atmosphere in Westminster.
Now, as MPs and ministers start packing their swimming costumes for the looming summer break, Mr Blair's steely determination to march on will be put to the test - again.
By the end of the week he will look forward to jetting off to his holiday retreat either with his leadership once again secure or possibly wondering whether he should bother coming back.
And once again it is the long shadow of Iraq threatening to block out his sunshine.
The week should get off to a pretty good start with Chancellor Gordon Brown delivering his annual spending review on Monday which should help set the course towards the next general election.
Mr Brown will lay out his plans for the post-general election period and has the task of persuading people that a vote for Labour will be a vote for even more resources for key areas such as law and order and transport.
Most important will be the chancellor's job of persuading voters just how he plans to pay for it all.
Any suggestion taxes will have to rise, or even that borrowing will increase - therefore arousing suspicions of tax rises to come - will not go down well.
More importantly for Mr Brown and Mr Blair is the fact that the chancellor's statement will be viewed under the microscope of his leadership ambitions.
Observers will be looking to see whether he has attempted to show not only what a good chancellor he is, but what a great prime minister he would make.
Things then start to get significantly more difficult for the prime minister.
Wednesday will see the publication of the Butler report into the "accuracy of intelligence " before the war on Iraq.
The prime minister set up the new inquiry, headed by the former cabinet secretary, after President Bush announced a similar probe in the US.
The terms of reference were seen as so limiting that the Liberal Democrats and, later, the Tories refused to take part, amid allegations it was set to be another "Hutton-style whitewash".
Lord Butler looked at Iraq intelligence
More recent speculation, however, has suggested Lord Butler has roamed wider than his brief and may well make significant pronouncements on the role of key figures such as intelligence chief John Scarlett and ex-prime ministerial communications chief Alastair Campbell.
That could have knock on effects for the prime minister who has already prepared the ground by admitting that WMD may never be found in Iraq.
Cynics, however, are pointing out that we heard all that before the Hutton inquiry reported.
Tony Blair will make a statement in the Commons following publication of the report amid strong feelings of Hutton deja vu.
That will be another of those great will he, won't he moments - assuming Butler is not so devastating as to have made his resignation unavoidable. That is not expected.
The very next day, Mr Blair faces two hugely difficult by elections in Birmingham Hodge Hill and Leicester South.
The word is that there is a very good chance Labour will lose the Leicester seat, held with a 13,000 majority at the last election, and could come within an ace of losing Birmingham's 11,000 majority.
The Liberal Democrats are certainly optimistic about Leicester, where there is a sizeable Muslim vote, and would love to pull off a sensation by taking Hodge Hill.
There may still be relief for the prime minister, however, if the Tories do particularly badly.
And, inevitably, Mr Blair would attempt to brush aside any disastrous performances as yet more protest voting along the lines of the recent local elections.
But all these things will play into the growing nervousness on the party's backbenches.
He has survived recent traumas and there has been no co-ordinated move for backbenchers to dump him.
This week's events could, of course, change all that. And this time it will not be the words of his cabinet friends that will carry the weight, it will be the response of his critics.