Up to 10 libraries have been earmarked for closure in Hampshire as part of plans to save £1.76m, the county council has said.
The news comes as the authority tries to cut £80m from its budget by 2021.
The proposals also include cutting the opening hours of its remaining 38 libraries by an average of 15%.
A council report said the impact on staff would depend on the number of closures but fewer closures would result in more job losses.
The libraries earmarked for closure are:
- Blackfield and Lyndhurst in the New Forest
- Chineham and South Ham in Basingstoke
- Elson and Lee-on-the-Solent in Gosport
- Emsworth in Havant
- Fair Oak in Eastleigh
- Horndean in East Hampshire
- Odiham in Hart
A second option is also being considered involving an average 25% reduction in staff hours across all 48 council-run libraries, meaning every library would remain open but for fewer hours.
But the report warned this would involve the greatest number of staff cuts, with 46 full-time roles disappearing, because fewer closures meant building-related savings would not be made.
In addition to the closures, the authority has announced plans to withdraw support for four community-managed libraries, which cost £49,000 a year to run.
Hampshire County Council said if communities running the libraries at Kingsclere, Lowford, Milford-on-Sea and North Baddesley did not wish to adopt a "new delivery model" they would close.
Recreation councillor Sean Woodward said: "We've seen in the last 10 years something like two million fewer books being issued per year so it's a huge change but we want to make sure that the libraries which are open are thriving, well run, well attended and well used by our residents."
Keith House, the leader of the opposition Liberal Democrat group, said: "I'm really disappointed. Hampshire have had years to work out how to fund their library service and now they are threatening to close a quarter of Hampshire's libraries, which is really not good enough."
About 400 people currently work for Hampshire's library service.
A consultation on the proposals will continue until March.