One in five voters believes students and others have every right to resort to violent protests if politicians break promises, an opinion poll suggests.
But a large majority were against anything but peaceful protests with almost two thirds backing the use by the police of water cannon to quell any disorder.
The latest survey by ComRes also revealed the extent of public disillusion with politicians – all three major party leaders suffering negative performance ratings.
Ed Miliband fared particularly badly in the poll – for the Independent on Sunday and the Sunday Mirror – with just 17% saying he was turning out to be a good leader.
Only 39% of Labour’s own supporters backed him but he may take hope from the fact that half of all those questioned had not made up their minds.
His party also slipped a point in the overall party standings although retains a two point advantage – by 39% to 37% – over the Conservatives who gained one.
The Liberal Democrats slipped one point to 11%, their lowest in a ComRes poll, with leader Nick Clegg facing the largest proportion – 48% – of voters expressing negative views of his leadership.
Prime Minister David Cameron had the smallest gap between fans and critics – 38% approving of his premiership so far and 40% disagreeing – and Mr Clegg the biggest at minus 23 points.
Half of those who voted Lib Dem at the general election disapprove of his leadership as he continues to attract anger over joining the coalition and broken promises on university tuition fees.
That issue has sparked scenes of violence on the streets of London in recent weeks as protests against moves to almost treble the cap on fees have descended into rioting.