New headache for Rachel Reeves as OBR expected to lower productivity forecast

Weaker growth outlook would set chancellor on course to break her fiscal rules without significant action in budget

The Office for Budget Responsibility is expected to downgrade its key productivity forecast, the Guardian understands, setting Rachel Reeves on course to break her fiscal rules without significant action in the budget.

The government's independent watchdog has carried out a stocktake" of its forecast models over the summer, and Treasury officials privately acknowledge the result will inevitably be a weaker growth outlook.