Cuts to Bath and North East Somerset Council are to be debated later.
More than 150 posts out of 4,000 are to go in the next financial year as councillors attempt to save £15.5m from a budget of £300m.
Funding is set to be withdrawn from youth services and some voluntary groups. The Conservative-run council wants to spend £33m on new offices.
But the Liberal Democrats say the cuts could be offset by refurbishing rather than rebuilding the Keynsham offices.
Lib Dem leader on the council, Paul Crossley, said it was a "grandiose project" that was "completely inappropriate".
"I don't think the public would understand £33m being spent on new council offices," he said.
The Lib Dems would instead use the money to do things like improve waste collection and street cleaning and to implement a 20mph speed policy in residential areas, he claimed.
The Conservatives have accused the Lib Dems of "short-term thinking" and claim the project will help regenerate the town and attract new employment.
Deputy leader of the council, Conservative Malcolm Hanney, said the project would include a new library, retail space and attract investment in the town.
"It will add to Keynsham's offer and it's important that it's regenerated. We need to be showing our commitment to Keynsham."
The council is also looking at outsourcing its adult social care to private companies.
The proposals will be debated in Bath's Guildhall on Tuesday evening.