Hundreds of projects for new schools, children's centres, libraries and roads across Oxfordshire are at risk, the county council says.
Earlier this year the council announced it was making £100m of cuts over the next five years.
Now it is reviewing £500m of capital building projects ahead of expected cuts in grants from central government this year.
A formal decision is not expected to be made until later in the year.
Keith Mitchell, leader of Oxfordshire County Council, said: "We have to look at every job and scheme and decide which should be given priority and which we may no longer take forward in the next five years.
"We won't make those decisions until later in the year, when we have far more detail about the precise shape and size of government funding.
"However, it is only fair to tell people now that we are once again forward planning responsibly and taking a fresh look at every scheme."
The council said it was too soon to say which schemes would be scrapped, but stressed there would be consultations over the coming weeks to help prioritise the importance of each project.
Mark Fysh, the Oxfordshire spokesperson for Unison, said: "If these cuts go ahead, it's not government, it's butchery.
"Public service is now on the brink of being dismantled and the public want public services that serve them.
"These are not made up jobs, these are front-line projects that people in this county need and deserve."