Reeves does nothing to ease roller coaster of budget speculation

There were times - quite a few of them in the past few months - when people speculated that Rachel Reeves would not survive as chancellor into the winter.

It has been an especially bruising year for the Chancellor of the Exchequer - from the tears in the House of Commons to the various U-turns over economic policy that left a black hole in her fiscal plans. So there was more than a little symbolism to the fact that she took to the stage today and dominated the first full day of Labour Party Conference.

Politics latest: Starmer ally 'not ruling out tax rises' Her performance was confident - more confident than many had expected. Relatively light on brand new economic policy, her speech is perhaps better described as a sort of highlights reel of Labour's "best bits" in office so far: more money for investment, more cash for schools, more funding for the NHS as well as rescues for British Steel and, just recently, Jaguar Land Rover.

Her problem, however, is that this tightly-controlled speech, part of a tightly-controlled conference, is the starting gun for something Ms Reeves has far less control over: the long roller-coaster towards the next budget. Later this week the Office for Budget Responsibility (OBR) will deliver its first estimate to the Treasury of the projected state of the public finances in the coming years.

While the OBR is a public body, it generates its own forecasts in secrecy, so while the Treasury has a team of economists trying to second-guess the OBR, no-one in Downing Street is entirely sure where it will end up. That estimate (which will be chopped and changed in the coming weeks as the budget approaches) is of supreme importance, because the chancellor has committed to a set of fiscal rules - limits on how high the current budget, and a measure of the national debt, could get.

And since the OBR's opinion on the state of the economy is what determines those numbers, the figures it delivers later this week are of outsize importance. Right now the speculation in government (note that for the time being this is purely speculation - no-one knows for sure what the OBR will say) is that the 'black hole' between the chancellor's fiscal rules and the OBR's latest estimates of the size of the current budget - is likely to be around £20bn to £30bn.

That is, for want of a better phrase, a lot of money - so much so that it's very hard to see how you could fill the gap with lots of little tax rises. Indeed, it's very hard, at the best of times, to raise tens of billions of pounds without resorting to one of the big three taxes in the UK: income tax, national insurance or VAT.

Labour's problem, however, is that it committed in its election manifesto last year not to raise any of those taxes. It is, in other words, penned in by a problem largely of its making.

Had it not committed to its fiscal rules, or to abiding by the word of the OBR, or to the manifesto tax pledge, it would have far more room for manoeuvre. As it is, it is facing a roller coaster of speculation in the run-up to the budget.

There will be many twists and turns in the coming weeks..