The Welsh Assembly Government is to publish its draft budget for the next three years later.
The £14.5bn budget covers spending across devolved areas including health, education and economic development.
Ministers from the Labour-Plaid Cymru coalition have said their budget will be cut by £1.8bn in real terms by 2014.
The assembly government is expected to protect education and health but spending on new infrastructure is expected to be cut.
A final decision on the budget will be made early next year, ahead of the next elections for the assembly, due to be held in May.
At the weekend, First Minister Carwyn Jones told the BBC schools, skills and hospitals would be priorities.
In England and Scotland, health spending is protected but the Welsh Assembly Government has decided against ringfencing, instead saying it will focus on protecting front-line services.
The Welsh Conservatives have made a pledge that they would protect the £6bn-plus health budget in its entirety and give it inflation-linked increases every year.
But this would mean severe cuts elsewhere in government expenditure and the party has not said where those would be made.
Mr Jones said free prescriptions and hospital parking would be maintained in the budget.
Gerry Holtham, who chaired the independent group looking at the way Wales is funded, told BBC Radio Wales that spending on infrastructure would be badly hit.
"The cuts over four years are about 7.5% in the ordinary budget but the really unpleasant looking cuts are 41% in the infrastructure budget," he said.
"Wales has rather under spent on infrastructure in recent years anyway.
"We haven't always spent all of our capital allocation so to have the capital allocation now cut by 41% is going to leave us very short of money for any infrastructure development, building schools, or anything else."
The draft budget will be published at 1500 GMT but the final budget will be some time in the New Year.