The AA has criticised plans to cut £46m from Somerset County Council's road maintenance budget.
The council blamed the move on government cutbacks but it prompted its cabinet member for transport, Antony Trollope-Bellew, to resign in protest.
The AA's Paul Watters said it would lead to "more claims against highways", more potholes and a bigger maintenance backlog.
Mr Trollope-Bellew said the cuts could put lives at risk.
The Conservative-controlled council has been told it will face a 25% cut in funding from central government over the next four years.
Council leader Ken Maddock said: "There are things we really didn't want to cut back on, but we just don't have a choice.
"We already have a huge debt so borrowing more is not an option - each year we pay out £36m towards our debt."
But Mr Trollope-Bellew said the decision would cost more in the long term and make roads unsafe.
"The skid resistance of the roads will get worse, the potholes will get worse, the potholes might even get deeper and this will lead to more accidents. The chances of increased fatalities are very high," he said.
The AA said each local authority in England already had on average a £5.6m backlog in road repairs.
"Local authorities are spending a big chunk of their budget on what we call reactive elements so they're going out dealing with the potholes - that's the symptom, but they're not dealing with the cause," Mr Watters said.
"If we don't deal with the cause we're going to spend more money firefighting than actually dealing with the problem."