Former Lib Dem councillor Karl Wallace has defected to the Labour Party.
Coun Wallace, 49, was elected to Bridport Town Council in 2003 and Dorset County Council in 2009.
Councillor Wallace says he made the move because he is concerned coalition government cutbacks could affect local NHS services.
He said: "I have joined the Labour Party because the Lib Dems have become Tories.
"The NHS is not safe in the coalition government's hands - you can see that the country is getting in a bigger mess.
"I am concerned about changes in the NHS. They are going to affect local services."
Richard Nicholls, chairman of Bridport and District Labour Party, said: "We welcome Karl coming across and we are aware that hundreds of Lib Dems are feeling very much the same - terribly let down by a party that used to be to the left of politics, rather than to the right "Locally, the Lib Dems want power without responsibility. While they argue against policies, it is their party pushing them into the public domain."
Labour has now launched a campaign in Bridport, opposing cutbacks to the NHS.
Coun Wallace lost his West Dorset District Council seat in May.
He had earlier been convicted of failing to provide a specimen of breath to police after a car crash.
He resigned from the Liberal Democrat Party in July and says he has been carefully considering his position since attending the Lib Dems' spring conference, held in Sheffield last March.
During the conference, he urged Nick Clegg to think again about university tuition fees.
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