More than 13,000 signatures have now been collected on a petition against library closures mounted by opposition Sheffield councillors.
Labour-run Sheffield Council says it may have to close up to 14 of 27 community libraries unless it can get other organisations to take over branches.
The authority has still not revealed which branches would be closed - and refused a request by The Star to name the third party groups it is in discussions with.
Coun David Baker, opposition Liberal Democrat spokesman for libraries, said: “Across the city, we’ve collected more than 13,000 signatures.
“Libraries don’t need to be sacrificed if Labour would cut down on office makeovers and political pet projects.
“It’s time for Labour to be open and honest about which libraries are on their hit list.”
Sheffield Council said revealing details about groups bidding to run libraries or which could be closed might prejudice negotiations.
More signatures were collected by Liberal Democrats in Ecclesfield at the weekend.