Bernie Sanders lashed out at a Democratic rival as the first debate in Detroit opened with a heated and lengthy row over healthcare options.

The veteran senator from Vermont, who is a longtime champion of a universal healthcare system that would cover all Americans, said his plans would include dental care, hearing aids and glasses for the elderly.

He was challenged by Ohio congressman Tim Ryan , who said: “You don’t know that.”

The exchange represented one of the main themes of the evening, as progressive candidates like Mr Sanders and Elizabeth Warren went on the attack against more moderate rivals like Mr Ryan and John Delaney.