Coalition MPs will attempt to derail Chancellor George Osborne's "pasty tax" when it is debated in the Commons today.
Liberal Democrats and Conservatives from Devon and Cornwall, including Prime Minister David Cameron's former press secretary George Eustice, want to block the bid to make pasties and other hot baked foods subject to 20% VAT.
They have tabled an amendment to the Finance Bill calling for no change to tax rates affecting baked products "when no attempt is made to keep the product hot for consumption".
It is at Commons Speaker John Bercow's discretion whether the clause gets selected this afternoon.
The move comes after hundreds of bakers announced they will march on Downing Street next week in protest over the tax changes.
Osborne announced the tax in last month's Budget, saying it would bring bakeries and supermarkets selling hot food in line with fast-food outlets which already pay VAT.